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.~