464 BOOK X. 



Finally, the gold is taken out of this and quenched, and if there is a 

 blackish colour settled in it, it is melted with a httle of the chrysocolla 

 which the Moors call borax ; if too pale, it is melted with stibium, and 

 acquires its own golden-yellow colour. There are some who take out the 

 molten copper with an iron ladle and pour it into another crucible, whose 

 aperture is sealed up with lute, and they place it over glowing charcoal, 

 and when they have thrown in the powders of which I have spoken, they 

 stir the whole mass rapidly with an iron rod, and thus separate the gold 

 from the copper ; the former settles at the bottom of the crucible, the latter 

 floats on the top. Then the aperture of the crucible is opened with the 

 red-hot tongs, and the copper runs out. The gold which remains is re-heated 

 with stibium, and when this is exhaled the gold is heated for the third time 

 in a cupel with a fourth part of lead, and then quenched. 



The fourth method is to melt one and a third librae of the copper 

 with a sixth of a libra of lead, and to pour it into another crucible smeared on 

 the inside with taUow or gypsum ; and to this is added a powder consisting of 

 half an uncia each of prepared sulphur, verdigris, and saltpetre, and an uncia 

 and a half of sal coctus. The fifth method consists of placing in a crucible 

 one libra of the copper and two librae of granulated lead, with one and a half 

 unciae of sal-artificiosus ; they are at first heated over a gentle fire and then 

 over a fiercer one. The sixth method consists in heating together a bes of 

 the copper and one-sixth of a libra each of sulphur, salt, and stibium. The 

 seventh method consists of heating together a bes of the copper and one-sixth 

 each of iron scales and fihngs, salt, stibium, and glass-galls. The eighth 

 method consists of heating together one libra of the copper, one and a half 

 librae of sulphur, half a libra of verdigris, and a libra of refined salt. The 

 ninth method consists of placing in one libra of the molten copper as 

 much pounded sulphur, not exposed to the fire, and of stirring it rapidly 

 with an iron rod ; the lump is ground to powder, into which quicksilver 

 is poured, and this attracts to itself the gold. 



Gilded copper articles are moistened with water and placed on the fire, 

 and when they are glowing they are quenched with cold water, and the gold 

 is scraped off with a brass rod. By these practical methods gold is separated 

 from copper. 



Either copper or lead is separated from silver by the methods which I 

 wiU now explain. 2^ This is carried on in a buUding near by the works, or 

 in the works in which the gold or silver ores or alloys are smelted. The 

 middle wall of such a building is twenty-one feet long and lifteen feet high, and 

 from this a front wall is distant fifteen feet toward the river ; the rear wall 



^^Throughout the book the cupellation furnace is styled the secunda fornax (Glossary, 

 Treibeherd). Except in one or two cases, where there is some doubt as to whether the author 

 may not refer to the second variety of blast furnace, we have used " cupellation furnace." 

 Agricola's description of the actual operation of the old German cupellation is less detailed 

 than that of such authors as Schliiter (Hiitte-Werken, Braunschweig, 1738) or Winkler (Besch- 

 reihung der Freyberger Schmelz Hultenprozesse, Freyberg, 1837). The operation falls into four 

 periods. In the first period, or a short time after melting, the first scum — the abzttg — arises. 

 This material contains most of the copper, iron, zinc, or sulphur impurities in the lead. 

 In the second period, at a higher temperature, and with the blast turned on, a second scum 



