s i97 1

As the black flux (which coniills of one part of nitre,and two or three of tartar, mixed together, and burnt ina covered vellel to a black alkaline coal) is apparently tooexpensive to be employed for any considerable quantities ofthe mineral; its place may be supplied by a mixture ofpotash, or other fixt alkaline salts, with powdered charcoal-.Four parts of potash, three of charcoal, and thirty-two oflead, are sufficient for sixteen of the calcined sand. Thismixture, as Hellot observes, requires the fire to be con-tinued longer than the preceding to make the matterequally fluid; but when it is made so, the yield is foundto be in both cafes alike.

The fame end may be obtained also, by boiling thecalcined sand in melted lead, without any inflammable orsaline addition. For the vitreous matter, into which thelead is gradually converted, will dissolve the earth, and theunvitrefied part of the lead will receive and collect thegold ; but a much larger quantity of lead is requisite in' this than in the other ways.

In all the foregoing methods, though the quantity ofgold obtained is considerable, much still remains in thescoriae, from want, probably, of a thorough commixtureof them with the lead : for whatever degree of fluiditythe scoriae are brought to, the particles of gold are toominute to subside by their own weight, and the lead cancollect them only from those parts which it comes incontact with. It may therefore be presumed, that theseparation will be the more complete, as the commixtureof the lead is the more perfect. Lead cannot be mixedperfectly with sands but in a vitreous or femivitreous form.By grinding the calcined sand with litharge or other calcesof lead, and exposing the mixture to a moderately strongfire, they may be intimately united into an uniform glassycompound ; the sand being dissolved by the vitrefied leach5 nearly