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contains more or less of it ; and that both the gold andtin ore have been brought from elsewhere by torrents ofwater, and deposited where they are now found like thegold sands of rivers.

Boyle conjectures, that besides the grains of gold whichlie detached among sands, there may be many particles sominute and closely fixed to the sand, as not to be per-ceivable by the eye, or separable by the common me-thods of wastiing or picking ; that many small portions ofthe metal may be incorporated also with the body of thesand, and that by skilful management they might be ex-tracted. Experiments, he fays, confirmed him in thispersuasion : later experiments have verified it, and shewnthe existence of gold in sands to be even more extensivethan he seems to have apprehended. Many of the com-mon sands, particularly the yellow, red, black, and thoseof a black colour inclining to violet, appear to be rich ingold: Becher and Cramer presume that there is no sandin nature entirely free from it. Hellot relates, that ineleven assays of one kind of sand, made by M. Lieberecht,by a process described in the sequel of this section, theyield of noble metal turned out constantly from eighthundred and forty to eight hundred and forty-four grainson the quintal or 921600 grains, exclusive of what. re-mained in the scoriæ, which were still found to be rich ;that different parcels of sand, taken up at no great dist-ance from one another, differed in degree of richness,some having afforded above a thousand grains, others onlythree hundred and fifty, and others yielding none by thetreatment which had succeeded so well for the rest ;and that of the metal thus obtained from sands twothirds are commonly gold, and the rest silver. Yetnotwithstanding the great richness of these sands, nomeans have hitherto been discovered of availing ourselves

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