4o6 BOOK IX. 



of the alloy there is a bes or three-quarters of silver. In this way every week, 

 if the work is for six days, thirty-six centumpondia of cakes are made and 

 three centumpondia of alloy, in all of which there is often almost twenty-four 

 librae of silver. The second smelter separates from the primary cakes the 

 greater part of the silver by absorbing it in lead. To eighteen centumpondia 

 of cakes made from crude copper ore, he adds twelve centumpondia of hearth- 

 lead and htharge, three centumpondia of stones from which lead is smelted, 

 five centumpondia of hard cakes rich in silver, and two centumpondia of 

 exhausted Uquation cakes*^ ; he adds besides, some of the slags resulting 

 from smelting crude copper, together with a small quantity of concentrates 

 made from accretions, all of which he melts for the space of twelve hours, 

 and makes eighteen centumpondia of secondary cakes, and twelve centum- 

 pondia of copper-lead-silver aUoy ; in each centumpondium of the latter 

 there is half a libra of silver. After he has taken off the cakes with a 

 hooked bar, he pours the alloy out into copper or iron moulds ; by this 

 method they make four cakes of alloy, which Eire carried to the works in 

 which silver is parted from copper. On the following day, the same smelter, 

 taking eighteen centumpondia of the secondary cakes, again adds twelve 

 centumpondia of hearth-lead and htharge, three centumpondia of stones 

 from which lead is smelted, five centumpondia of hard cakes rich in silver, 

 together with slags from the smelting of the primary cakes, and with concen- 

 trates washed from the accretions which are usually made at that time. 

 This charge is hkewise smelted for the space of twelve hours, and he makes as 

 many as thirteen centumpondia of tertiary cakes and eleven centumpondia 

 of copper-lead-silver alloy, each centumpondium of which contains one- 

 third of a libra and half an uncia of silver. When he has skimmed off the 

 tertiary cakes with a hooked bar, the alloy is poured into copper moulds, and 

 by this method four cakes of alloy are made, which, hke the preceding four 

 cakes of aUoy, are carried to the works in which silver is parted from copper. 

 By this method the second smelter makes primary cakes on alternate days 

 and secondary cakes on the intermediate days. The third smelter takes 

 eleven cartloads of the tertiary cakes and adds to them three cartloads of 

 hard cakes poor in silver, together with the slag from smelting the secondary 

 cakes, and the concentrates from the accretions which are usually made 

 at that time. From this charge when smelted, he makes twenty centum- 

 pondia of quaternary cakes, which are called " hard cakes," and also 

 fifteen centumpondia of those " hard cakes rich in silver," each centum- 

 pondium of which contains a third of a libra of silver. These latter cakes the 

 second smelter, as I said before, adds to the primary and secondary cakes 

 when he re-melts them. In the same way, from eleven cartloads of qua- 

 ternary cakes thrice roasted, he makes the " final " cakes, of which one 

 centumpondinm contains only half an uncia of silver. In this operation he 

 also makes fifteen centumpondia of " hard cakes poor in silver," in each 

 centumpondium of which is a sixth of a libra of silver. These hard cakes the 



**Exhausted liquation cakes (panes aerei fathiscentes). This is the copper sponge resulting 

 from the first liquation of lead, and still contains a considerable amount of lead. The liquation 

 process is discussed in great detail in Book XI. 



