490

BOOK X.

muffle has small windows at the sides, and in front a little bridge. In orderto melt the silver, at the sides of the muffle are laid bricks, upon which thecharcoal is placed, and burning firebrands are put on the bridge. Thefurnace has an iron door, which is covered on the side next to the fire with lutein order that it may not be injured. When the door is closed it retains theheat of the fire, but it has a small window, so that the artificers may lookinto the test and may at times stimulate the fire with the bellows. Althoughby this method silver is refined more slowly than by the other, nevertheless it ismore useful, because less loss is caused, for a gentle fire consumes fewer particlesthan a fierce fire continually excited by the blast of the bellows. If, onaccount of its great size, the cake of silver can be carried only with difficultywhen it is taken out of the muffle, they cut it up into two or threepieces while it is still hot, with a wedge or a hammer-chisel; for if they cutit up after it has cooled, little pieces of it frequently fly off and are lost.

END OF BOOK X.