BOOK XI. 507 



lead, and in four cakes of this kind there are three centumpondia of copper and 

 twelve centumpondia of lead. The lead which is hquated therefrom weighs 

 about ten centumpondia, in each centiimpondium of which there is a quarter 

 of a libra and more than a semi-uncia of silver, or seven unciae ; a hes, or 

 seven unciae and a semi-uncia, of silver remain in the exhausted hquation 

 cakes and in the hquation thorns. 



Against the second long wall in the second part of the building, whose 

 area is eighty feet long by thirty-nine feet wide, are four furnaces in which 

 the copper is alloyed with lead, and six furnaces in which " slags " are re- 

 smelted. The interior of the first kind of furnace is a foot and three pakns wide, 

 two feet three digits long ; and of the second is a foot and a palm wide and a foot 

 three palms and a digit long. The side walls of these furnaces are the same 

 height as the furnaces in which gold or silver ores are smelted. As the whole 

 room is divided into two parts by upright posts, the front part must have, 

 first, two furnaces in which " slags " are re-melted ; second, two furnaces in 

 which copper is alloj^ed with lead ; and third, one furnace in which " slags " are 

 re-melted. The back part of the room has first, one furnace in which " slags " 

 are re-melted ; next, two furnaces in which copper is alloyed with lead ; and 

 third, two furnaces in which " slags " are re-melted. Each of these is six feet 

 distant from the next ; on the right side of the first is a space of three feet 

 and two palms, and on the left side of the last one of seven feet. Each pair of 

 furnaces has a common door, six feet high and a cubit wide, but the first and 

 the tenth furnace each has one of its own. Each of the furnaces is set in an arch 

 of its own in the back wall, and in front has a f orehearth pit ; this is filled with 

 a powder compound rammed down and compressed in order to make a crucible. 

 Under each furnace is a hidden receptacle for the moisture, ^^ from which a 

 vent is made through the back wall toward the right, which allows the 

 vapour to escape. Finally, to the right, in front, is the copper mould into 

 which the copper-lead alloy is poured from the forehearth, in order that 

 liquation cakes of equal weight may be made. This copper mould is a digit 

 thick, its interior is two feet in diameter and six digits deep. Behind the 

 second long wall are ten pairs of bellows, two machines for compressing them, 

 and twenty instruments for inflating them. The way in which these should 

 be made may be understood from Book IX. 



The smelter, when he alloys copper with lead, with his hand throws into 

 the heated furnace, first the large fragments of copper, then a basketful of 

 charcoal, then the smaller fragments of copper. When the copper is melted 

 and begins to run out of the tap-hole into the forehearth, he throws htharge 

 into the furnace, and, lest part of it should fly away, he first throws 

 charcoal over it, and lastly lead. As soon as he has thrown into the furnace 

 the copper and the lead, from which alloy the first liquation cake is made, he 

 again throws in a basket of charcoal, and then fragments of copper are thrown 

 over them, from which the second cake may be made. Afterward with a 

 rabble he skims the " slag " from the copper and lead as they flow into the 

 forehearth. Such a rabble is a board into which an iron bar is fixed ; the 



"See p. 356. 



