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BOOK VII.

copper is not wholly liquefied ; if he finds this is the case, he again places alarge piece of charcoal in the crucible, and replaces the glowing charcoal whichhad been removed, and again blows the bellows for a short time. When allthe copper has melted he stops using the bellows, for if he were to continueto use them, the fire would consume part of the copper, and then that whichremained would be richer than the cake from which it had been cut; this isno small mistake. Therefore, as soon as the copper has become sufficientlyliquified, 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 theassay. The mould has a handle, likewise made of iron, by which it is heldwhen the copper is poured in, after which, he plunges it into a tub of waterplaced near at hand, that the copper may be cooled. Then he again dries thecopper by the fire, and cuts off its point with an iron wedge ; the portionnearest the point he hammers on an anvil and makes into a leaf, which hecuts into pieces.

A—Iron mould. B—Its handle.

Others stir the molten copper with a stick of linden tree charcoal, andthen pour it over a bundle of new clean birch twigs, beneath which is placeda wooden tub of sufficient size and full of water, and in this manner the copperis broken up into little granules as small as hemp seeds. Others employ strawin place of twigs. Others place a broad stone in a tub and pour in enoughwater to cover the stone, then they run out the molten copper from thecrucible on to the stone, from which the minute granules roll off ; otherspour 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 pouredand a thin leaf made of it, or unless it has been resolved into granules ormade into filings ; and if it does not melt, all the labour has been undertakenin vain. In order that they may be accurately weighed out, silver and leadare resolved into granules in the same manner as copper. But to returnto the assay of copper. When the copper has been prepared by thesemethods, 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 containsiron, add two undue. First put the lead into a cupel, and after it beginsto smoke, add the copper; the fire generally consumes the copper, togetherwith the lead, in about one hour and a quarter. When this is done, the silver