452 BOOK X. 



a siciUcus of copper is added ; and if it contains no copper, then half an 

 uncia, because copper must be added to stibium in order to part gold from 

 silver. The gold is first placed in a red hot earthen crucible, and when 

 melted it swells, and a little stibium is added to it lest it run over ; in a 

 short space of time, when this has melted, it likewise again swells, and 

 when this occurs it is advisable to put in all the remainder of the stibium, 

 and to cover the crucible with a lid, and then to heat the mixture for the 

 time required to walk thirty-five paces. Then it is at once poured out into 

 an iron pot, wide at the top and narrow at the bottom, which was first 

 heated and smeared over with taUow or wax, and set on an iron or wooden 

 block. It is shaken violently, and by this agitation the gold lump settles 

 to the bottom, and when the pot has cooled it is tapped loose, and is again 

 melted four times in the same way. But each time a less weight of stibium 

 is added to the gold, until finally only twice as much stibium is added as 

 there is gold, or a little more ; then the gold lump is melted in a cupel. The 

 stibium is melted again three or four times in an earthen crucible, and each 

 time a gold lump settles, so that there are three or four gold lumps, and 

 these are all melted together in a cupel. 



To two librae and a half of such stibium are added two librae of argol 

 and one libra of glass-galls, and they are melted in an earthen crucible, 

 where a lump likewise settles at the bottom ; this lump is melted in the 

 cupel. Finally, the stibium with a little lead added, is melted in the cupel, 

 in which, after all the rest has been consumed by the fire, the silver alone 

 remains. If the stibium is not first melted in an earthen crucible with argol 

 and glass-galls, before it is melted in the cupel, part of the silver is consumed, 

 and is absorbed by the ash and powder of which the cupel is made. 



The crucible in which the gold and silver alloy are melted with stibium, 

 and also the cupel, are placed in a furnace, which is usually of the kind 



frothing," and recommend that the crucible should be only partly filled. As to the copper, 

 we suggest that it would desulphurize part of the antimony and thus free some of that metal 

 to collect the gold. If we assume bullion of the medium fineness mentioned and containing 

 no copper, then the proportions in the first charge would be about 36 parts gold, 12 parts 

 silver, 41 parts sulphur, 103 parts antimony, and 9 parts copper. The silver and copper 

 would take up 4.25 parts of sulphur, and thus free about 10.6 parts of antimony as metallics. 

 It would thus appear that the amount of metallics provided to assist the collection of the 

 gold was little enough, and that the copper in freeing 5.6 parts of the antimony was useful. 

 It appears to have been necessary to have a large excess of antimony sulphide ; for even 

 with the great surplus in the first charge, the reaction was only partial, as is indicated by the 

 necessity for repeated melting with further antimony. 



The later metallurgists all describe the separation of the metallic antimony from 

 the gold as being carried out by oxidation of the antimony, induced by a jet of air into the 

 crucible, this being continued until the mass appears limpid and no cloud forms in the surface 

 in cooling. Agricola describes the separation of the silver from the regulus by preliminary 

 melting with argols, glass-gall, and some lead, and subsequent cupellation of the lead-silver 

 alloy. The statement that unless this preliminary melting is done, the cupel will absorb 

 silver, might be consonant with an attempt at cupellation of sulphides, and it is difficult to see 

 that much desulphurizing could take place with the above fluxes. In fact, in the later 

 descriptions of the process, iron is used in this melting, and we are under the impression 

 that Agricola had omitted this item for a desulphurizing reagent. At the Dresden Mint, 

 in the methods described by Percy (Metallurgy Silver and Gold, p. 373) the gold lumps were 

 tested for fineness, and from this the amount of gold retained in the regulus was computed. 

 It is not clear from Agricola's account whether the test with nitric acid was appUed to the 

 regulus or to the " lumps". For historical notes see p. 461. 



