BOOK X. 457 



and to wash it with warm water. Finally, it is placed in a bowl, and, when 

 dry, the granules or leaves are rubbed against a touchstone at the same time 

 as a touch-needle, and considered carefully as to whether they be pure or 

 alloyed. If they are not pure enough, the granules or the leaves, together 

 with the cement which attracts silver and copper, are arranged alternately 

 in layers in the same manner, and again heated ; this is done as often as is 

 necessary, but the last time it is heated as many hours as are required to 

 cleanse the gold. 



Some people add another cement to the granules or leaves. This cement 

 lacks the ingredients of metalliferous origin, such as verdigris and vitriol, for 

 if these are in the cement, the gold usually takes up a little of the base metal ; 

 or if it does not do this, it is stained by them. For this reason some very 

 rightly never make use of cements containing these things, because brick 

 dust and salt alone, especially rock salt, are able to extract all the silver and 

 copper from the gold and to attract it to themselves. 



It is not necessary for coiners to make absolutely pure gold, but to heat 

 it only until such a fineness is obtained as is needed for the gold money which 

 they are coining. 



The gold is heated, and when it shows the necessary golden yellow colour 

 and is wholly pure, it is melted and made into bars, in which case they are 

 either prepared by the coiners with chrysocolla, which is called by the Moors 

 borax, or are prepared with salt of lye made from the ashes of ivy or of 

 other salty herbs. 



The cement which has absorbed silver or copper, after water has been 

 poured over it, is dried and crushed, and when mixed with hearth-lead and 

 de-silverized lead, is smelted in the blast furnace. The alloy of silver and 

 lead, or of silver and copper and lead, which flows out, is again melted in the 

 cupellation furnace, in order that the lead and copper may be separated from 

 the silver. The silver is finally thoroughly purified in the refining furnace, 

 and in this practical manner there is no silver lost, or only a minute quantity. 



There are besides this, certain other cements 20 which part gold from 

 silver, composed of sulphur, stibium and other ingredients. One of these 

 compounds consists of half an uncia of vitriol dried by the heat of the fire 

 and reduced to powder, a sixth of refined salt, a third of stibium, half a libra 



20 The processes involved by these " other " compounds are difficult to understand, 

 because of the lack of information given as to the method of operation. It might be thought 

 that these were five additional recipes for cementing pastes, but an inspection of their 

 internal composition soon dissipates any such assumption, because, apart from the lack of 

 brickdust or some other similar necessary ingredient, they all contain more or less sulphur. 

 After describing a preliminary treatment of the bullion by cupellation, the author says : 

 " Then the silver is sprinkled with two unciae of that powdered compound and is 

 " stirred. Afterward it is poured into another crucible .... and violently shaken. 

 " The rest is performed according to the process I have already explained." As he has 

 already explained four or five parting processes, it is not very clear to which one this refers. 

 In fact, the whole of this discussion reads as if he were reporting hearsay, for it lacks in every 

 respect the infinite detail of his usual descriptions. In any event, if the powder was intro- 

 duced into the molten bullion, the effect would be to form some silver sulphides in a regulus 

 of different composition depending upon the varied ingredients of different compounds. 

 The enriched bullion was settled out in a " lump " and treated " as I have explained," 

 which is not clear. 



