GUNPOWDER, a composition of nitre, sulphur, and charcoal, mixed together, and usually granulated; which easily takes fire, and, when fired, rarefies or expands with great vehemence, by means of its elastic force. It is to this powder we owe all the action and effect of guns, ordnance, &c. so that the modern military art, fortification, &c. in a great measure depend thereon. Invention of GUNPOWDER. See GUN. Method of making GUNPOWDER. Dr Shaw's receipt for this purpose is as follows: Take four ounces of refined nitre, an ounce of sulphur, and six drams of small-coal: reduce these to a fine powder, and continue beating them for some time in a stone mortar with a wooden pestle, wetting the mixture between whiles with water, so as to form the whole into an uniform paste, which is reduced to grains, by passing it through a wire-sieve fit for the purpose; and in this form being carefully dried, it becomes the common gunpowder. For greater quantities mills are usually provided, by means of which more work may be performed in one day than a man can do in a hundred. The nitre or saltpetre is refined thus: Dissolve four pounds of rough nitre as it comes to us from the Indies, by boiling it in as much water as will commodiously suffice for that purpose: then let it shoot for two GUN or three days in a covered vessel of earth, with sticks laid across for the crystals to adhere to. These crystals being taken out, are drained and dried in the open air. In order to reduce this salt to powder, they dissolve a large quantity of it in as small a portion of water as possible; then keep it constantly stirring over the fire till the water exhales, and a white dry powder is left behind. In order to purify the sulphur employed, they dissolve it with a very gentle heat; then scum and pass it through a double strainer. If the sulphur should happen to take fire in the melting, they have an iron cover that fits on close to the melting vessel, and damps the flame. The sulphur is judged to be sufficiently refined if it melts, without yielding any fetid odour, between two hot iron plates, into a kind of red substance. The coal for making gunpowder is either that of willow or hazel, well charged in the usual manner, and reduced to powder. And thus the ingredients are prepared for making this commodity: but as these ingredients require to be intimately mixed, and as there would be danger of their firing if beat in a dry form, the method is to keep them continually moist, either with water, urine, or a solution of sal ammoniac; they continue thus stamping them together for 24 hours; after which the mass is fit for corning and drying.