474

BOOK X.

and thick ; with these he pushes the sticks of wood forward and the barsthen rest on the trestles. There are others who, when they separate metals,put two such sticks of wood into the crucible through the aperture which isbetween the bellows, as many through the holes at the back, and one throughthe channel; but in this case a larger number of long sticks of wood isnecessary, that is, sixty ; in the former case, forty long sticks of wood sufficeto carry out the operation. When the lead has been heated for two hours,it is stirred with a hooked bar, that the heat may be increased.

If it be difficult to separate the lead from the silver, he throws copperand charcoal dust into the molten silver-lead alloy. If the alloy of argen-tiferous gold and lead, or the silver-lead alloy, contains impurities from theore, then he throws in either equal portions of argol and Venetian glass or ofsal-ammoniac, or of Venetian glass and of Venetian soap ; or else unequalportions, that is, two of argol and one of iron rust; there are some whomix a little saltpetre with each compound. To one centumpondium of thealloy is added a bes or a libra and a third of the powder, accordingto whether it is more or less impure. The powder certainly separates theimpurities from the alloy. Then, with a kind of rabble he draws out through

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A —Furnace. B —Sticks of wood. C —Litharge. D—Plate. E —The foreman

WHEN HUNGRY EATS BUTTER, THAT THE POISON WHICH THE CRUCIBLE EXHALES MAY NOTHARM HIM, FOR THIS IS A SPECIAL REMEDY AGAINST THAT POISON.