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BOOK X.
ounces of the alloy contain only five drachmae of copper or at most six, forif there is more copper in it, the silver separated from the gold soon uniteswith it again. Such molten silver containing gold is formed into granules,being stirred by means of a rod split at the lower end, or else is poured into aniron mould, and when cooled is made into thin leaves. As the process ofmaking granules from argentiferous gold demands greater care and diligence thanmaking them from any other metals, I will now explain the method briefly. Thealloy is first placed in a crucible, which is then covered with a lid and placedin another earthen crucible containing a few ashes. Then they are placedin the furnace, and after they are surrounded by charcoal, the fire is blownby the blast of a bellows, and lest the charcoal fall away it is surroundedby stones or bricks. Soon afterward charcoal is thrown over the uppercrucible and covered with live coals ; these again are covered with charcoal,so that the crucible is surrounded and covered on all sides with it. Itis necessary to heat the crucibles with charcoal for the space of half an hour ora little longer, and to provide that there is no deficiency of charcoal, lest thealloy become chilled ; after this the air is blown in through the nozzle of thebellows, that the gold may begin to melt. Soon afterward it is turnedround, and a test is quickly taken to see whether it be melted, and if it ismelted, fluxes are thrown into it; it is advisable to cover up the crucibleagain closely that the contents may not be exhaled. The contents are heatedtogether for as long as it would take to walk fifteen paces, and then thecrucible is seized with tongs and the gold is emptied into an oblong vesselcontaining very cold water, by pouring it slowly from a height so that thegranules will not be too big ; in proportion as they are lighter, more fineand more irregular, the better they are, therefore the water is frequentlystirred with a rod split into four parts from the lower end to the middle.
The leaves are cut into small pieces, and they or the silver granules areput into a glass ampulla, and the aqua is poured over them to a height of adigit above the silver. The ampulla is covered with a bladder or with waxedlinen, lest the contents exhale. Then it is heated until the silver is dissolved,the indication of which is the bubbling of the aqua. The gold remains in thebottom, of a blackish colour, and the silver mixed with the aqua floats above.Some pour the latter into a copper bowl and pour into it cold water, whichimmediately congeals the silver ; this they take out and dry, having pouredoff the aqua n . They heat the dried silver in an earthenware crucible untilit melts, and when it is melted they pour it into an iron mould.
The gold which remains in the ampulla they wash with warm water,filter, dry, and heat in a crucible with a little chrysocolla which is calledborax, and when it is melted they likewise pour it into an iron mould.
“ it until the lead has incorporated itself . . . blow it until it plickt ( blickens ). Then
“ you will have as much silver as before.”
u The silver is apparently precipitated by the copper of the bowl. It would seemthat this method was in considerable use for small amounts of silver nitrate in the 16thCentury. Lazarus Ercker gives elaborate directions for this method (Beschreibung Atter-furnemsten, etc., Prague, 1574, p. 77).