512 



BOOK XI. 



shall be made caldarium copper. But when the copper, yeUow or red or caldar- 

 ium is re-smelted in the refining furnace, forty centumpondia are placed in 

 it, and from it they make at least twenty, and at most thirty-five, centum- 

 pondia. About twenty-two centumpondia of exhausted liquation cakes and 

 ten of yellow copper and eight of red, are simultaneously placed in this latter 

 furnace and smelted, in order that they may be made into refined copper. 



The copper " bottoms " are alloyed in three different ways with lead.^' 

 First, five-eighths of a centumpondium of copper and two and three- 

 quarters centumpondia of lead are taken ; and since one Uquation cake is made 

 from this, therefore two and a half centumpondia of copper and eleven cen- 

 tumpondia of lead make four liquation cakes. Inasmuch as in each centumpon- 

 dium of copper there is a third of a libra of silver, there would be in the whole 

 of the copper ten-twelfths of a libra of silver ; to these are added four centum- 

 pondia of lead re-melted from " slags," each centumpondium of which contains 

 a sicilicus and a drachma of silver, which weights make up a total of an uncia 

 and a half of silver. There is also added seven centumpondia of de-silverized 

 lead, in each centumpondium of which there is a drachma of silver ; therefore 

 in the four cakes of copper-lead alloy there is a total of a libra, a sicilicus and 

 a drachma of silver. In each single centumpondium of lead, after it has been 

 liquated from the copper, there is an uncia and a drachma of silver, which alloy 

 we caU " poor " argentiferous lead, because it contains but little silver. But 

 as five cakes of that kind are placed together in the furnace, they liquate 

 from them usually as much as nine and three-quarters centumpondia of poor 



*'The liquation of these low-grade copper " bottoms " required that the liquated lead 

 should be re-used again to make up fresh liquation cakes, in order that it might eventually 

 become rich enough to warrant cupellation. In the following table the " poor " silver-lead 

 is designated (A) the " medium " (B) and the " rich " (C). The three charges here given 

 are designated sixth, seventh, and eighth for purposes of reference. It will be seen that the 

 data is insufficient to complete the ninth and tenth. Moreover, while the author gives direc- 

 tions for making four cakes, he says the charge consists of five, and it has, therefore, been 

 necessary to reduce the volume of products given to this basis. 



Amount of copper bottoms 



Amount of lead . . 



Amount of de-silverized 

 lead 



Weight of each cake 



Average value of charge 

 per ton 



Per cent, of copper 



Average value per ton 

 original copper 



Average value per ton of . . 



Average value per ton of . . 



Weight of liquated lead . . 



Average value of the liqu- 

 ated lead per ton 



Weight of exhausted liqu- 

 ation cakes 



Average value of the ex- 

 hausted liquation cakes 

 per ton . . 



Weight of liquation thorns 



Average value of the liqu- 

 ation thorns per ton . . 



Extraction of silver into 

 the liquated lead 



