Mr. Mushet made some valuable experiments on the carbonization and incineration of coals. He found that the Scotch cannel-coal afforded 56.57 volatile matter, 39.43 charcoal, and 4 ashes; while the stone-coal, found under basalt, gave 16.66 volatile matter, 69.74 charcoal, and 13.6 ashes, and oak wood, 80.00 volatile matter, 19.5 charcoal, and 0.5 ashes. The quantity of gas, however, depends entirely on the quality of the coal. A temperature of about 600° to 700° is sufficient to disengage it. A pound of good cannel coal, properly treated in a small apparatus, will yield five cubic feet of gas, equivalent in illuminating power to a mould candle, six in the pound. One pound of coal, on a large scale, affords only 3-1/2 cubic feet of gas. A gas jet, which consumes half a cubic foot per hour, gives a steady light equal to that of a candle of the above-mentioned size. The cannel coal, known in Scotland by the name of parrot coal, is very inflammable, takes fire immediately, and produces a brilliant flame. It is used by the poor as a substitute for candles. This coal, we have seen, furnishes an abundance of carburetted hydrogen gas. It has the appearance of jet, and admits of being turned in a lathe. Stone coal, Kilkenny coal, Welch coal, and glance coal consist almost entirely of charcoal; and hence, when laid on burning coals, they become red-hot, emit a blue lambent flame, in the same manner as charcoal, and at length are wholly consumed, leaving behind a portion of red ashes. They burn without smoke or soot. The pitch coal, which has a brownish-black colour, and is generally found massive in plates, the bovey coal, called brown coal, and bituminous wood, with the anthracite coal, and some others of lesser note, form the remaining varieties of coal.