Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . le, at the proper time, is mantled (as theworkmen call it) or covered with a layer ofalready calcined and exhausted ore, in orderto protect it from high winds and heavy rains;as also to moderate the heat, and let it pro-ceed gradually, so that the sulphur prese
Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . le, at the proper time, is mantled (as theworkmen call it) or covered with a layer ofalready calcined and exhausted ore, in orderto protect it from high winds and heavy rains;as also to moderate the heat, and let it pro-ceed gradually, so that the sulphur presentmay not be lost or wasted by roasting is finally checked by a thicker mantling, and the whole allowed to cool. Bythis time the pile has usually lost about onehalf its bulk, and become open and porous inthe interior, so that the air can circulate freelythrough the mass; the latter, in di-y weather,as the heap cools, being usually promoted bysprinkling a little water on it, which, by carry-ing down some of the saline matter, rendersthe interior still more open to the whole, v,?hen cold, or nearly cold, is, ifnecessary, still further exposed to the action ofair and moisture. The time required to calcinethe heap properly, including that taken by theburned ore to cool, varies, according to its size. and the state of the weather, from tnree tonine, or even twelve months. The residuum ofthe calcination is next placed in large stone orbrick cisterns, and edulcorated with water,until all the soluble portion is dissolved out;the solution is then concentrated in anotherstone cistern,so made that the flame and heatedair of its reverberatory fiirnace sweep the wholesurface of the liquor. (See engr.) The evapo-ration is continued until it just harely reachesthe point at which crystals are deposited oncooling; when it is run off into coolers. Afterthe sulphate of iron, always present, has beendeposited in crystals, the mother liquor, con-taining the sulphat
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