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BOOK XII.

of the same size and shape, and without a spout, but having three holes, two ofwhich are below the mouth and receive the spouts of the two first pots ; thethird hole is on the opposite side at the bottom, and through it the sulphurflows out. In each furnace are placed two pots with spouts, and the furnacemust be covered by plates of iron smeared over with lute two digits thick ; it isthus entirely closed in, but for two or three ventholes through which the mouthsof the pots project. Outside of the furnace, against one side, is placed the potwithout a spout, into the two holes of which the two spouts of the other potspenetrate, and this pot should be built in at both sides to keep it steady. Whenthe sulphur ore has been placed in the pots, and these placed in the furnace,they are closely covered, and it is desirable to smear the joint over with lute,so that the sulphur will not exhale, and for the same reason the pot below iscovered with a lid, which is also smeared with lute. The wood having beenkindled, the ores are heated until the sulphur is exhaled, and the vapour,arising through the spout, penetrates into the lower pot and thickens intosulphur, which falls to the bottom like melted wax. It then flows outthrough the hole, which, as I said, is at the bottom of this pot; and the work-man makes it into cakes, or thin sticks or thin pieces of wood are dipped in it.Then he takes the burning wood and glowing charcoal from the furnace, andwhen it has cooled, he opens the two pots, empties the residues, which, if theores were composed of sulphur and earth, resemble naturally extinguishedashes ; but if the ores consisted of sulphur and earth and stone, or sulphurand stone only, they resemble earth completely dried or stones well roasted.Afterward the pots are re-filled with ore, and the whole work is repeated.

The sulphurous mixture, whether it consists of stone and sulphur only,or of stone and sulphur and metal, may be heated in similar pots, but withperforated bottoms. Before the furnace is constructed, against the “ second ”wall of the works two lateral partitions are built seven feet high, three feetlong, one and a half feet thick, and these are distant from each other twenty-seven feet. Between them are seven low brick walls, that measure buttwo feet and the same number of digits in height, and, like the other walls,are three feet long and one foot thick; these little walls are at equaldistances from one another, consequently they will be two and one half feetapart. At the top, iron bars are fixed into them, which sustain iron platesthree feet long and wide and one digit thick, so that they can bear not onlythe weight of the pots, but also the fierceness of the fire. These plates havein the middle a round hole one and a half digits wide ; there must not bemore than eight of these, and upon them as many pots are placed. Thesepots are perforated at the bottom, and the same number of whole pots areplaced underneath them ; the former contain the mixture, and are coveredwith lids; the latter contain water, and their mouths are under the holesin the plates. After wood has been arranged round the upper pots andignited, the mixture being heated, red, yellow, or green sulphur dripsfrom it and flows down through the hole, and is caught by the pots placedunderneath the plates, and is at once cooled by the water. If the mixturecontains metal, it is reserved for smelting, and, if not, it is thrown away.