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the weight upon the bellows; and the alternate injection,of the subject-matter and of charcoal continued. Themetal and flag, melting and dropping down through thecoals, are collected in the bottom : when they are ofsuch a kind as to melt with difficulty, it is necessary, inorder to their being continued in thin fusion, to directthe pipe of the bellows downwards, toward the oppositeside of the bottom : the aperture is made to admit of thebellows being readily thus directed, without wideningit in the middle, by sloping off a little, from its upperedge on the outside, and from the lower edge within.

When iron is thus to be melted (an intention for whichthis furnace is extremely well adapted) or copper to bepurified, among the coals, the black lead pot performs theoffice both of a crucible and of a furnace. In this caseit is necessary to have its bottom surrounded on the out-side with burning fuel: the liftings and small fragmentsof charcoal, unfit for other uses, answer sufficiently forthis purpose, for they are soon set on fire by the heat ofthe pot, and serve, as well as the larger pieces, to main-'s tain and augment its heat : they may be placed in a cavitymade in the ground, or in the bottom of another vessel.When the process is finished, the melted metal may bepoured out, by inclining the pot, through the hole wherethe pipe of the bellows entered.

But when litharge is to be revived, or the ores of leador of the other more fusible and destructible kinds of me-tals to be smelted,- the metal, in propofticn as it is col-lected in the bottom, must be suffered to run off fromthe vehement heat and blast of air; for which purpose apassage is to be made for it in the most depending part,and a bason filled with coals placed conveniently on theoutside for receiving it. The lower part of a black lead pot,sawed off at a proper height, as three or four inches above

the