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XCV. There is alſo a kind of this made of Ochre, by burning, but it is not nearly ſo good as the others. The making this was an Invention of Cydias, who took the Hint of it, as is ſaid, from obſerving, in a Houſe which was on fire, that ſome Ochre which was there, when half burnt, aſſumed a red Colour.
XCVI. The way of making the factitious is this: They put the Ochre into new earthen Veſſels, which they cover with Clay and ſet in Furnaces; and theſe, as they grow hot, heat alſo the Ochre, and the greater Degree of Fire they give, the deeper and more ſtrongly purple the Matter becomes. The Origin of the native Kinds ſeems to teſtify that this Method is not irrational, for all theſe ſeem to have ſuffered Changes by the Action of Fire:
which was dug in the New Jerſeys in America, where it is frequently found at about 15 or 20 Feet deep, and is called, (I ſuppoſe from its Colour and ſtaining the Hands) Blood-ſtone. It was originally uſed, not only in Painting, but in Medicine; and though now neglected, and not known in the Shops, deſerves to be brought into Uſe again, being a much better
