250 



BOOK VII. 



copper is not wholly liquefied ; if he finds this is the case, he again places a 

 large piece of charcoal in the crucible, and replaces the glowing charcoal which 

 had been removed, and again blows the bellows for a short time. When all 

 the copper has melted he stops using the bellows, for if he were to continue 

 to use them, the fire would consume part of the copper, and then that which 

 remained would be richer than the cake from which it had been cut ; this is 

 no small mistake. Therefore, as soon as the copper has become sufficiently 

 liquified, he pours it out into a little iron mould, which may be large or small, 

 according as more or less copper is melted in the crucible for the purpose of the 

 assay. The mould has a handle, likewise made of iron, by which it is held 

 when the copper is poured in, after which, he plunges it into a tub of water 

 placed near at hand, that the copper may be cooled. Then he again dries the 

 copper by the fire, and cuts off its point with an iron wedge ; the portion 

 nearest the point he hammers on an anvil and makes into a leaf, which he 

 cuts into pieces. 



A IRON MOULD. B ITS HANDLE. 



Others stir the molten copper with a stick of linden tree charcoal, and 

 then pour it over a bundle of new clean birch twigs, beneath which is placed 

 a wooden tub of sufficient size and full of water, and in this manner the copper 

 is broken up into little granules as small as hemp seeds. Others employ straw 

 in place of twigs. Others place a broad stone in a tub and pour in enough 

 water to cover the stone, then they run out the molten copper from the 

 crucible on to the stone, from which the minute granules roll off ; others 

 pour the molten copper into water and stir it until it is resolved into granules. 

 The fire does not easily melt the copper in the cupel unless it has been poured 

 and a thin leaf made of it, or unless it has been resolved into granules or 

 made into filings ; and if it does not melt, all the labour has been undertaken 

 in vain. In order that they may be accurately weighed out, silver and lead 

 are resolved into granules in the same manner as copper. But to return 

 to the assay of copper. When the copper has been prepared by these 

 methods, if it is free of lead and iron, and rich in silver, to each centumpon- 

 dium (lesser weights) add one and a half undue of lead (larger weights). If, 

 however, the copper contains some lead, add one uncia of lead ; if it contains 

 iron, add two undue. First put the lead into a cupel, and after it begins 

 to smoke, add the copper ; the fire generally consumes the copper, together 

 with the lead, in about one hour and a quarter. When this is done, the silver 



