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its precipitates by alcalies having nothing of the fulmi-nating power, which precipitates of gold possess in a moreeminent degree than any other known kind of matter; itssolutions in aqua regia suffering no decomposition from es-sential oils or æther, by both which gold is imbibed fromthe acid, nor from inflammable spirits by which gold is re-vived and thrown out in its proper form; its being reject-ed, on trituration, from its solution in quicksilver, whilegold is retained and continues dissolved; its being separablefrom gold, in virtue of these diversities of affinity, withoutaugmentation or diminution of either metal, as easily andas perfectly as any one metal is separable from any other;are characters abundantly more than sufficient for establish-ing a specific difference between platina and gold.

3. The author of the letter from Venice, mentioned inpage 447, enters into some alchemical speculations on thissubject, which the nature of the present history requiresthat I should give some account of. He imagines, that asplatina is a species of the same genus with gold, its dif-ferences from gold are only accidental, preceding eitherfrom some heterogeneous body radically united with it, orfrom the want of a glutinous tinging sulphur. To whichof these causes its imperfection is owing, he does not de-termine: its being less ponderous than gold, the blackpoints discovered on its grains by a microscope, and a partof it being precipitated from aqua regia by alcalies while apart continues dissolved, are brought as arguments for theformer; its want of fusibility, its solution wanting thepower of staining animal substances and of producing apurple with tin, and its not being separated from its so-lution by inflammable liquors which have an affinity withsulphurs; for the latter. In the one case by purging theplatina of its heterogeneous matter, and in the other byintroducing the tinging sulphur, he thinks it will become,gold. This last, it seems, is easy enough to be done,.

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