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 ever formed any Subtance that could be properly o called; all that I have been hewn as uch, having been Things which a little Chemitry was able to hew that Naturalits ought to have been ahamed of calling by uch a Name: Not that I would pretend to limit the Operations of Nature within the Bounds of our narrow Undertandings; or declare any Thing impoible, becaue it has not yet been een to be effected: But I think the Aertors of uch great Effects from o very uncertain a Subtance, ought, if ever they had een it, to have given a more rational Account of it than any we have at preent.

The Zaffer we know, and with which the blue Glas and counterfeit Sapphires are tained, is a Preparation which eems to owe its preent Mode of Exitence to the extreme Force of Fire; and is perhaps no genuine Production of Nature, even in a latent State, except in its contituent Principles. It is prepared from Cobalt, affording, by the Aitance of Fire, the Arenics, this Subtance; and Smalt, with the Addition of a fixed Alkali. After the Fire of a reverberatory Furnace has driven off the arenical Particles, the remaining Mas is powdered and calcined three or four Times over; and then being mixed with three Times its Quantity of powdered Flints, affords us the common Zaffer.

But it may be proper to examine what Weight, even allowing the Exitence of a tive