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most pot, in its lower part, through opposite holesmade for that purpose, served for a grate: the fuel,and the crucible containing the metal, were put in at themouth of the pot: a hole in the side, made under thegrate, admitted air to the fuel: and the upper invertedpot, having a hole cut in its top, supplied the place bothof a dome and chimney. By this means he could melt,with ease and expedition, several ounces of gold at atime; and conveniently examine the metal, during thefusion, by raising or lifting off the upper pot.

A judicious variation of this simple contrivance promisedto afford furnaces of more extensive utility. Black leadpots appeared peculiarly well fitted for this use; commonexperience having shewn, that they bear vehement fireswithout melting, repeated or continued fires withoutbeing so liable to fail as any of the other kinds of cru-cibles, and quick vicissitudes of heat and cold withoutbeing so liable to crack : on these properties their excel-lence as crucibles depends. They have another quality,inessential to them as crucibles, but which particularlyadapts them to the making of furnaces: they admit freelyof being ground, drilled, sawed with a common toothedsaw, and cut with any kind of edged or pointed tool; sothat the necessary doors, groovings, &c. may be readilymade in them with common instruments, and stoppersfor the doors formed out of broken pieces.

Having seen two of these crucibles form a convenientmelting furnace where only a moderate fire was required:it was plain that a stronger fire might be excited in themby the means used for that purpose in other furnaces,viz. a bellows or a chimney; that one crucible wouldserve as a furnace for those uses in which no dome iswanted; and that if the upper crucible was fitted up inthe same manner as the lower, it would in such case be adistinct furnace os itself. It remained therefore to deter-

mine