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Bretagh’s account printed inHarris’s collection, the commonyield is no more than five or six ounces of gold upon thecaxon or fifty hundred pounds of the mineral: the richestmines afford only ten or twelve ounces, and those whichare but just rich enough to pay the charges of working ofthem, yield only two ounces on that quantity. It may beobserved in general, that the quantity of gold in mineralsis more variable than that of other metals in their ores,and the profits of a gold mine more precarious ; this me-tal not being formed into any regular veins, or uniformlydistributed through any particular kind of earth or stone,but scattered as it were here and there through differentmineral bodies : when united with other metals in theirores, its proportion is by no means constant, though inthis cafe it is subject to much less variation than when itis barely bedded in earths or stones.

Of the source of the gold of the East Indies and ofAfrica, we know but little. From Cape-coast on thecoast of Guinea we receive yearly between two and threethousand ounces of gold dust, which is supposed to becollected from the sands of rivers ; and some Europeantraders are said to have been witnesses of the richness ofthe sands in certain parts of that coast. In Hook’s post-humous papers an account is given of a person havingmet with great quantities of gold in the sands of one ofthe rivers, the sand seeming to grow richer and richeras he advanced further up : in some places he fays hegained sixty-three grains of gold from five pounds ofsand, and he seems afterwards to have met with muchmore profitable spots. Three or four hundred ounces, asI am informed, are collected yearly from the sands ofthe Gambia, and cast into bars at James-fort, one of oursettlements on that river. i

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