528

BOOK XI.

or after two hours, if it was soft and fragile. The workman adds charcoal tothem where he sees it is needed, throwing it into the furnace through theopenings on both sides between the side walls and the closed door. This open-ing is a foot and a palm wide. He lets down the door, and when the “ slags ”begin to flow he opens the passages with a bar ; this should take place afterfive hours ; the door is let down over the upper open part of the arch fortwo feet and as many digits, so that the master can bear the violence of theheat. When the cakes shrink, charcoal should not be added to them lestthey should melt. If the cakes made from poor and fragile copper are“ dried ” with cakes made from good hard copper, very often the copperso settles into the passages that a bar thrust into them cannot penetratethem. This bar is of iron, six feet and two palms long, into which a woodenhandle five feet long is inserted. The refiner draws off the “ slags ” with arabble from the right side of the hearth. The blade of the rabble is madeof an iron plate a foot and a palm wide, gradually narrowing toward thehandle; the blade is two palms high, its iron handle is two feet long, andthe wooden handle set into it is ten feet long.

When the exhausted liquation cakes have been “ dried,” the master

A —The door raised. B —Hooked bar. C —Two-pronged rake. D—Tongs.

E—Tank.

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