OBSERVATIONS ON THE MANUFACTURE OF GUNPOWDER ON THE CONTINENT AND AMERICA.
It may not be uninteresting to have a slight knowledge of the method employed on the Continent, &c., for the production of Gunpowder.
Proportion of the ingredients.
The proportions of the three ingredients vary slightly all over the Continent and America, being as follows:—
| SALTPETRE. | CHARCOAL. | SULPHUR. | |||
|---|---|---|---|---|---|
| France | - | 75 | 12.5 | 12.5 | |
| Belgium | |||||
| Russia | 73.78 | 13.59 | 12.63 | ||
| Prussia | 75 | 13.5 | 11.5 | ||
| Austria | 75.5 | 13.2 | 11.3 | ||
| Spain | 76.47 | 10.78 | 12.75 | ||
| United States | 76 | 14 | 10 | ||
PRODUCTION AND PURIFICATION OF THE INGREDIENTS.
Production and purification of the ingredients.
The nitre is purified in a similar way to the new method employed at Waltham Abbey, though it is seldom obtained with so faint a trace of chlorides, owing probably to its being of an inferior quality, and of higher refraction when it is imported.
The sulphur is supplied to the manufactories in France in the form of roll sulphur, from Marseilles and Bordeaux, where there are very large refineries.
The charcoal is prepared from dogwood, alder, willow, hazel, and poplar, sometimes in pits, and occasionally in cylinders, as at Waltham Abbey. At Wetteren, and in some parts of France, it is distilled by the action of steam. The “charbon roux” taking its name from its brownish-red tinge, from being only partially burned, was used formerly more than now, as the powder made from it was found to injure and exert very pernicious effects upon fire-arms.
PULVERIZING AND MIXING THE INGREDIENTS.
Pulverizing and mixing the ingredients.
The ingredients are generally pulverized in copper drums, capable of holding 224 kilogrammes. Part of the charcoal is mixed with the sulphur, and part of the sulphur with the saltpetre. They are then put into separate drums, which revolve about twenty-five times per minute for three hours, and in which are about 500 gun-metal or bronze balls, the size of good large marbles. The ingredients are brought to the most minute state of division by these means, and are then mixed all together, for one hour, in similar drums covered with leather, containing wooden balls.
INCORPORATING PROCESS.
Incorporation.
The fine powder thus obtained is sometimes merely moistened, so as to form a stiff paste, and passed through rollers, the cake formed, being dried and granulated. The incorporating cylinders are used occasionally, but the more usual plan adopted on the Continent to effect this operation is the stamping-mill, which requires a short description. It is nothing more nor less than the pestle-and-mortar principle, each mill consisting of from six to twelve bronze or wooden mortars bedded in the floor of the building; they are the shape of the frustum of a cone, the mouth being much narrower than the base; the pestles, or stampers as they are called, are made of wood, shod with either very hard wood or bronze, on which project wooden teeth about twelve inches long; a vertical movement is imparted to them by a shaft worked by the water-wheel having similar teeth attached; in its revolution it raises the stamper about eighteen inches, which falls again as the projection is disengaged, twenty five times in a minute. This operation is carried on for twelve hours, during which period the charge (about 15lbs.) is moistened at intervals, and routed up with a copper-shod spud; at the end of this time the cake is taken out, and left to dry and harden; it seldom receives any pressure—although, in some manufactories, presses are being erected.
GRANULATING.
Granulation.
The cake is then granulated in sets of sieves fitting one into the other, having perforated zinc bottoms of different degrees of fineness, which are suspended from the ceiling of the room by ropes, an ash spring being attached to each box holding the sieves, the cake is put into the uppermost one with some gun-metal balls, and shaken backwards and forwards, which motion the spring facilitates; it is thus broken up into different sized grains, which are separated by passing through the several meshes.
The grain formed is then dusted in bags or shaking-frames covered with canvas, and then glazed in barrels.
STOVING OR DRYING.
Drying.
In summer the process of drying is often performed in the sun, and in winter by the steam stove, in the following way. The powder is spread about three or four inches thick on a large canvas tray, under which is an arrangement of pipes, which convey the hot air forced by a fan through a cylinder heated by steam: it is considered to be sufficiently dried in from three to four hours, during which time it is occasionally raked about. In some manufactories it undergoes a further operation of being dusted, and is then barrelled up for use. Generally the great failure in the foreign manufacture is the neglect of the principal stage of the fabrication, viz. incorporation; with the old stamping-mill, it is quite impossible that the process can be carried out to the necessary extent. Comparative merits of foreign and English gunpowder.The Continental powder is usually very soft in its grain, dusty, and quickly absorbs moisture from the atmosphere; its density is below the English powder, on account of its never being subjected to pressure; consequently it is not so durable, and forms a good deal of dust in transport; a great amount of residue is generally left in the gun, and its strength, as a propelling agent, is far inferior to our powders. On being flashed on a glass plate, instead of producing a sudden concussion, like the sharp rap of a hammer, it burns more like composition, throwing off a quantity of sparks.