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other Bodies mixt with it; and to be altered in its Condition by that Mixture: But 'tis itſelf the ſame. Wallerius diſtinguithes three Degrees of Hardneſs in this Foſſil; but they are owing to thoſe Mixtures; the leaſt hard is the true Condition of Spar; the other Degrees ariſe from Iron, or other Additions.
It is the Opinion of Linnæus, that Spar owes its angulated Form to Sea Salt; and the Cryſtals to other Salts: But there is no Warrant in Nature for this Judgment. Salts are acrid, and diſſolve in Water. Theſe Foſſils have neither of thoſe Qualities: And who ſhall tell us that the Property of forming itſelf into regularly angulated Figures is peculiar to Salts? We have no Authority to believe it is wanting in Cryſtal, and Spar; and we have the Evidence of our Senſes that they have it.
The ingenious and ingenuous Cronſtedt well obſerves, theſe Figures ought not to be aſcribed to Salts, till the Preſence of ſuch Salts can be proved in them.
The calcarious Nature of Spar is of its Eſſence; and no Form, nor all the other Characters in the World, could conſtitute a Thing a Spar that wanted this. They all ferment with Acids, and they burn to Lime: Nor is this latter Quality equivocal, as ſome would think, becauſe by the Fire of a great Burning Glaſs, Spar vitrifies. This is not the Fire, when we ſpeak of Lime; and it can be a Teſt of nothing becauſe all Things vitrify before it:
That
