Charcoal being a preservative by which the saltpetre and the brimstone is made into gun-powder, by preventing the sulphur from suffocating the strong and windy exhalation of the nitre. There are several sorts of wood made use of for this purpose; some prefer hazle, others willow and alder; but there being so little difference, you may make use of either which is most convenient to be got. And the method of burning the wood is this: Cut it in pieces about one or two feet long, then split each piece in four parts; scale off the bark and hard knots, and dry them in the sun or in an oven, then make in the earth a square hole, and line it with bricks, in which lay the wood, crossing one another, and set it on fire; when thoroughly lighted and in a flame, cover the hole with boards, and fling earth over them close, to prevent the air from getting in, yet so as not to fall among the charcoal, and when it has lain thus for twenty-four hours, take out the coals and lay them in a dry place for use. It is to be observed that charcoal for fireworks must always be soft and well burnt, which may be bought ready done. To make Artificial CAMPHOR. Camphor, in the Materia medica, “is a body of a particular nature, being neither a resin, nor a volatile salt, nor an oil, nor a juice, nor a bitumen, nor a gum, but a mixed substance, dry, white, transparent and brittle, of a strong and penetrating smell. The Indians distinguish two kinds of it, a finer and a coarser; the finer is the produce of Borneo and Sumatra, is very rare, and is hardly ever sent into Europe; the coarser is the Japonese kind, which is the common sort, both in the Indies and in Europe. “The camphor, which we meet with in the shops, is also of two kinds, differing in regard to the degree of their purity, and distinguished by the name of rough and refined camphor. The tree, which produces camphor, is a species of bay tree, every part of which abounds with camphor; but is not collected from it in the manner of resins, but by a sort of chemical process.――The natives of the place where the trees grow, cut the wood and roots into small pieces. And put them into large copper vessels, which they cover with earthen heads, filled with straw; they give a moderate fire under them, and the camphor is raised in form of a white downy matter, and retained among the straw; when the process is over, they shake it out of the straw, and knead it into cakes. These cakes is are not very compact, but easily crumbled to pieces; they are moderately heavy, of a greyish or dusky reddish white in colour, of a pungent smell and acrid taste, and are what we call rough camphor. “Refined camphor must be chosen of a perfectly clean white colour, very bright and pellucid, of the same smell and taste with the rough, but more acrid and pungent.――It is so volatile that merchants usually inclose it in lin-seed, that the viscosity of that grain may keep its particles together.”