BOOK X.

483

The cupellation furnace in Poland and Hungary is likewise vaulted at thetop, and is almost similar to an oven, but in the lower part the bed is solid,and there is no opening for the vapours, while on one side of the crucible is awall, between which and the bed of the crucible is a passage in place of theopening for vapours ; this passage is covered by iron bars or rods extendingfrom the wall to the crucible, and placed a distance of two digits from eachother. In the crucible, when it is prepared, they first scatter straw, and thenthey lay in it cakes of silver-lead alloy, and on the iron bars they lay wood,which when kindled heats the crucible. They melt cakes to the weight of some-times eighty centum-pondia and sometimes a hundred centumpondia 33 . Theystimulate a mild fire by means of a blast from the bellows, and throw on to thebars as much wood as is required to make a flame which will reach into thecrucible, and separate the lead from the silver. The litharge is drawn outon the other side through an aperture that is just wide enough for the masterto creep through into the crucible. The Moravians and Cami, who veryrarely make more than a bes or five-sixths of a libra of silver, separatethe lead from it, neither in a furnace resembling an oven, nor in the cruciblecovered by a dome, but on a crucible which is without a cover and exposed tothe wind ; on this crucible they lay cakes of silver-lead alloy, and over themthey place dry wood, and over these again thick green wood. The woodhaving been kindled, they stimulate the fire by means of a bellows.

I have explained the method of separating lead from gold or silver. NowI will speak of the method of refining silver, for I have already explainedthe process for refining gold. Silver is refined in a refining furnace,over whose hearth is an arched chamber built of bricks ; this chamberin the front part is three feet high. The hearth itself is five feet longand four wide. The walls are unbroken along the sides and back, butin front one chamber is placed over the other, and above these and thewall is the upright chimney. The hearth has a round pit, a cubit wide and twopalms deep, into which are thrown sifted ashes, and in this is placed a preparedearthenware “ test,” in such a manner that it is surrounded on all sidesby ashes to a height equal to its own. The earthenware test is filledwith a powder consisting of equal portions of bones ground to powder, and ofashes taken from the crucible in which lead is separated from gold or silver;others mix crushed brick with the ashes, for by this method the powderattracts no silver to itself. When the powder has been made up andmoistened with water, a little is thrown into the earthenware test and tampedwith a wooden pestle. This pestle is round, a foot long, and a palm and adigit wide, out of which extend six teeth, each a digit thick, and a digit and athird long and wide, and almost a digit apart; these six teeth form a circle,and in the centre of them is the seventh tooth, which is round and of thesame length as the others, but a digit and a half thick; this pestle tapers alittle from the bottom up, that the upper part of the handle may be roundand three digits thick. Some use a round pestle without teeth. Then a

T 9 /t^ I ^ CO - a means the German centner, this charge would be from about 4.6 to 5.7 shorttons. If he is using Roman weights, it would be from about 3 to 3.7 short tons.