To recover damaged GUNPOWDER. The method of the powder-merchants is, to put part of the powder on a sail-cloth, to which they add an equal weight of what is really good; and with a shovel mingle it well together, dry it in the sun, and barrel it up, keeping it in a dry and proper place. Others again, if it be very bad, restore it by moistening it with vinegar, water, urine, or brandy; then they beat it fine, scarce it, and to every pound of powder add an ounce, an ounce and a half, or two ounces, according as it is decayed, of melted saltpetre. Afterwards, these ingredients are to be moistened and mixed well, so that nothing can be discerned in the composition, which may be known by cutting the mass; and then they granulate it as before. In case the powder be in a manner quite spoiled, the only way is to extract the saltpetre with water according to the usual manner, by boiling, filtering, evaporating, and crystallizing; and then with fresh sulphur and charcoal to make it up anew again.
In regard to the medical virtues of gunpowder, Boerhaave informs us, that the flame of it affords a
very healthy fume in the height of the plague, because the explosive acid vapour of nitre and sulphur corrects the air; and that the same vapour, if received in a small close pent-up place, kills insects.
It is enacted by 5 and 11 of Geo. I. and 5 Geo. II. c. 20. that gunpowder be carried to any place in a covered carriage; the barrels being close-jointed; or in cases and bags of leather, &c. And persons keeping more than 200 pounds weight of gunpowder at one time, within the cities of London and Westminster, or the suburbs, &c. are liable to forfeitures if it be not removed; and justices of the peace may issue warrants to search for, seize, and remove the same.