or RED-LEAD. See Chemistry, §° 402.

The general method of preparing that colour is there described; but the following more accurate and particular one hath appeared in the last edition of the Chemical Dictionary. "The furnace in which miniun is made is of the reverberatory kind, with two fire-places at the ends; each fire-place being separated from the area, or body of the furnace, by a wall 12 inches high. The fire-places are 15 inches broad, and their length is equal to the breadth of the whole furnace, which is about eight or nine feet. The length of the area from one fire-place to the other is 9 or 10 feet. The quantity of lead used in one operation is about 1500 pounds, of which nine parts are lead obtained from furnaces where the ore is melted, and one part is lead extracted from the scoria which is formed in smelting the ore. This latter kind is said to be necessary, as the former could not alone be reduced into powder. All the lead is at once put into the area, the bottom of which is level. The calx, as fast as it is formed, is drawn to one side by means of a rake suspended by a chain before the mouth of the furnace. In four or five hours the whole quantity of the lead is calcined, or, if any pieces remain uncalcined, they are separated, and kept for the next operation. The heat employed is that of a cherry-red; and the fire-places and mouth are kept open, that the air may accelerate the calcination. The powder or calx is to be frequently stirred to prevent its concreting; and when this operation has been continued about 24 hours, the matter is taken out of the furnace, and laid on a flat pavement. The cold water is thrown on it, to give it weight, as the workmen say; but rather, as some think, to make it friable. It is then to be ground in a mill, and the finer... Miner's finer part is separated by washing, while the coarser part, referred for some following operation, is to be placed at the mouth of the furnace in order to retain the melted lead. The fine powder, which is now of a yellow colour, is again put into the same or a similar furnace, and exposed to a very moderate fire from 36 to 48 hours; during which time it is stirred frequently to prevent its concreting; and the powder gradually acquires its proper red colour. The minium is then to be taken out of the furnace, cooled, and sifted through an iron sieve placed in a cask."