400 BOOK IX. 



made richer, to eighteen librae of it are added forty-eight librae of crude 

 ore, three librae of the stone from which iron is made, and three-quarters 

 of a libra of the cakes made from pyrites, and mixed with lead, all are 

 heated together in the crucible until they melt. When the slag and the 

 cakes melted from pyrites have been skimmed off, the alloy is carried to 

 other furnaces. 



There now follows silver, of which the native silver or the lumps of rudis 

 silver 34 obtained from the mines are not smelted in the blast furnaces, but in 

 small iron pans, of which I will speak at the proper place ; these lumps 

 are heated and thrown into molten silver-lead alloy in the cupellation furnace 

 when the silver is being separated from the lead, and refined. The tiny flakes 

 or tiny lumps of silver adhering to stones or marble or rocks, or again the 

 same little lumps mixed with earth, or silver not pure enough, should be 

 smelted in the furnace of which the tap-hole is only closed for a short time, 

 together with cakes melted from pyrites, with silver slags, and with stones 

 which easily fuse in fire of the second order. 



In order that particles of silver should not fly away 35 from the lumps 

 of ore consisting of minute threads of pure silver and twigs of native silver, 

 they are enclosed in a pot, and are placed in the same furnace where the rest of 

 the silver ores are being smelted. Some people smelt lumps of native silver 

 not sufficiently pure, in pots or triangular crucibles, whose lids are sealed with 

 lute. They do not place these pots in the blast furnace, but arrange them in 

 the assay furnace into which the draught of the air blows through small holes. 

 To one part of the native silver they add three parts of powdered litharge, as 

 many parts of hearth-lead, half a part of galena 36 , and a small quantity of 

 salt and iron-scales. The alloy which settles at the bottom of the other 

 substances in the pot is carried to the cupellation furnace, and the slags are 

 re-melted with the other silver slags. They crush under the stamps and 

 wash the pots or crucibles to which silver-lead alloy or slags adhere, and 

 having collected the concentrates they smelt them together with the slags. 

 This method of smelting rudis silver, if there is a small quantity of it, is the 

 best, because the smallest portion of silver does not fly out of the pot or the 

 crucible, and get lost. 



If bismuth ore or antimony ore or lead ore 37 contains silver, it is 

 smelted with the other ores of silver ; likewise galena or pyrites, if there is 

 a small amount of it. If there be much galena, whether it contain a large 

 or a small amount of silver, it is smelted separately from the others ; 

 which process I will explain a little further on. 



**Rudis silver comprised all fairly pure silver ores, such as silver sulphides, chlorides, 

 arsenides, etc. This is more fully discussed in note 6, p. 108. 



35 Evolent, volatilize ? 



**Lapidis plumbarii facile liquescentis. The German Translation gives glantz, i.e., Galena, 

 and the Interpretatio also gives glantz for lapis plumbarius. We are, however, uncertain 

 whether this " easily melting " material is galena or some other lead ore. 



"Molybdaena is usually hearth-lead in De Re Metallica, but the German translation 

 in this instance uses pleyertz, lead ore. From the context it would not appear to mean hearth- 

 lead saturated bottoms of cupellation furnaces for such material would not contain 

 appreciable silver. Agricola does confuse what are obviously lead carbonates with his other 

 molybdaena (see note 37, p. 476). 



