GIINP OW DE It is explosive nitre brought into intimate contact with in flammable sulphur and charcoal. 75 of the nitre, 16 of charcoal, and 9 of sul phur, pounded as paste with wooden mortars, fixed in a wheel for 12 hours. It is granulated by being forced through a sieve, and glazed by agitation in a cask. The gas formed by an explosion is 2 volumes of nitrogen to 1 carbonic acid.
Dr. lire has analysed various samples of gunpowder,'and the following are the results of his investigations : Waltham Abbey, nitre 74.5, charcoal 14.4, sulphur 10.0, water 1.1.
Hall, Dartford, nitre 76.2, charcoal 14.0, sulphur 9.0, water 0.5.
Pigou and Wilks, nitre 77.4, charcoal 13.5, sulphur 8.5, water 0.6.
Curtis and Harvey, nitre 76'7, charcoal 12.5, sulphur 9.0, water 1.1.
Battle gunpowder, nitre 77.0, charcoal 13.5, sulphur 8.0, water 0.8.
Charcoal, sulphur, and nitre, being ready for manufacturing into gunpowder. 1st. They are separately ground to a fine powder, which is passed through proper silk sieves or bolting machines. 2d. They are mixed together in the proper proportions. 3d. The composition is then sent t the gunpowder mill, which consists of two edge-stones of a calca reous kind, turning by means of a hori zontal shaft on a bed-stone of the same nature ; incapable of affording sparks by collision with steel. On this bed-stone the composition is spread, and moistened with as small a quantity of water as will, in conjunction. with the weight of the re volving stones, bring it into a proper body of cake, but by no means to a pasty state. The line of contact of the rolling edge-stone is constantly preceded by a hard copper scraper. which goes round with the wheel, regularly collecting the caking-mass, and bringing it into the track of the stone.
The materials for gunpowder are ground by a wheel revolving in a trough. They are then moistened and put into boxes with holes in the bottoms. The boxes are placed in a circular frame suspended by cords, and briskly agitated by a crank, when thepaste passes through the holes as corns of powder. These are afterwards polished by being revolved in a barrel, dried by vessels of steam, and packed for sale.
Gunpowder to be good should be quick, strong, free from impurity, and not liable to absorb moisture. The gene
ral method of trying the purity is by burning it on clean white paper two or three small heaps are made near each other, and one of them is fired ,• if the smoke rises perpendicularly, and there be no feculent matter left on the paper, nor the other heaps fired, it is considered that the ingredients were of agood qual ity, and well compounded. If the other heaps are fired, the paper burnt, or a dirty residuum left, it may be supposed that the nitre was impure, or that the charcoal was not completely pulverized.
M. Angendre, Assayer at the Mint of Constantinople, has addressed a commu nication to the Academy of Sciences at Paris, describing the discovery of a new explosive powder, having for its base the prussiate of potash. The composition is (by weight) crystallized dry yellow prus slate of potash one part, dry white sugar one part, chlorate of potash one part. These three substances are reduced se parately in a mortar to fine powder, and then intimately mixed by hand. In ope rating on any quantity, the mixture is moistened with a very little water, and beaten in a bronze mortar with a wooden pestle. It is not necessary that the mix ture should be as intimate as in the case of ordinary gunpowder,—a quarter of an hour will suffice to mix it. It is then grained in the ordinary manner, and dried in the air. The discoverer, M:An gendre, considers that this powder is equal in strength to three times its weight of the common kind. It is easily made, and the substances of which it is composed have a fixed and determined composition. It is not injured either in dry or damp air, but it is not suitable for small fire-arms only for those of east iron, and it will answer a good purpose in blasting. The reason why it is not good for any fire-arms of steel is owing to the chlorate of potash, which oxidizes steel with great rapidity. Some of our civil engineers may find this powder in valuable for blasting, as they can make it themselves, it being equally as effec tive when in a state of powder as when grained. No other powder must be al Towed to mix with it, for in ramming the bore for a blast, the friction of the parti cles of the old powder will be ready to ignite the new kind.