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 It has been aid, that Iland Cryftal hines in the Dark after it has been calcined in Manner of the Bolonian Stone; but this is not particular to that Species: It is the Quality of all Spar as Spar; only there requires great Nicety in the Calcination: Perhaps Selenite alo has this Power. Linnæus refers the Bolonian Stone to Spars: To me it has appeared rather a Selenite; and of all Bodies in Nature, mot of Kin to that Species of Selenite we call the Star, upon the waxen Vein. I have therefore retained it in that Place, till more of this carce Foil comes in my Way for Trial: If it proves Spar, 'tis eaily removed into that Clas; and thus, and only thus, we can arrive at Truth; after a thouand Errors.

That the Hog Spar affords Flowers on Sublimation, has been urged as a great Proof of its containing Salts of ome Kind or other; known or unknown: But urely this Property is more naturally reolved into another Source. All Bitumens yield Flowers on Sublimation; and we have the Tetimony of our Senes to the Preence of a Bitumen in the Lapis Suillus: It tinks of it. Nay more, there is a Smell of Sulphur in all Spar, when calcined: Henkel and Wallerius, as well as I, have found it; and if we could give way to any Thought of Secondary Forms in a Foil whoe Contruction appears perfectly homogene, and imple, my Sene of it would be, not to eek them in imaginary Salts, but real Sulphur. We