Gunpowder is a mixture of nitre, sulphur, and charcoal, and the more
completely they are mixed, the more finely ground, and the purer they
are, the more perfect will be the gunpowder. The proportions used of
these ingredients differ slightly in different powder mills; but the
average is about seventy-four parts nitre, ten sulphur, and fourteen
charcoal, by weight; the sulphur and nitre can easily be completely
purified, but the charcoal differs very much in almost every
specimen, and charcoal that has been burnt long ago and exposed to
the air and moisture is almost unfit for the purpose, that charcoal
which has the least ash when burnt is found to be the best, and the
charcoal which has been made in iron cylinders, is better than that
made in the usual way, when each of the ingredients are separately
powdered and sifted through a kind of sieve of silk called a bolting
machine (such as is used in dressing flour), they are mixed in the
proper proportions and taken to the mill, where they are moistened
with water and ground to a smooth paste, this is pressed hard and
then broken up into pieces which are put into a copper sieve, the
bottom of which is perforated with small hole; a flat wooden ball is
put into each sieve with the pieces of damp powder, and the sieves
are all put into a circular motion by machinery, this causes the
wooden ball to turn round in the sieve and so rub the damp powder
through the little holes; it is collected below in small grains or
“corns,” this process is called “corning,” this is now dried, and
then put into a “reel” (a sort of barrel which turns round) and
the grains, by rubbing against each other, become smoothed on the
surface; the dust is now removed by a sieve, too fine to let the
grains through; the powder is now fit for use.
Gunpowder was first known in England about five hundred years ago.
It is not only used to discharge firearms, but in the more peaceful
occupations of quarrying stone, mining, and to get rid of rocks both
below and above water; these processes are called “blasting.”