528 



BOOK XL 



or after two hours, if it was soft and fragile. The workman adds charcoal to 

 them where he sees it is needed, throwing it into the furnace through the 

 openings 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 after 

 five hours ; the door is let down over the upper open part of the arch for 

 two feet and as many digits, so that the master can bear the violence of the 

 heat. When the cakes shrink, charcoal should not be added to them lest 

 they should melt. If the cakes made from poor and fragile copper are 

 " dried " with cakes made from good hard copper, very often the copper 

 so settles into the passages that a bar thrust into them cannot penetrate 

 them. This bar is of iron, six feet and two palms long, into which a wooden 

 handle five feet long is inserted. The refiner draws off the " slags " with a 

 rabble from the right side of the hearth. The blade of the rabble is made 

 of an iron plate a foot and a palm wide, gradually narrowing toward the 

 handle ; the blade is two palms high, its iron handle is two feet long, and 

 the wooden handle set into it is ten feet long. 



When the exhausted liquation cakes have been " dried," the master 



A — The door raised 



-Hooked bar. C — Two-pronged rake. D — Tongs. 

 E — Tank. 



