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 other Bodies mixt with it; and to be altered in its Condition by that Mixture: But 'tis itelf the ame. Wallerius ditinguithes three Degrees of Hardnes in this Foil; but they are owing to thoe Mixtures; the leat hard is the true Condition of Spar; the other Degrees arie from Iron, or other Additions.

It is the Opinion of Linnæus, that Spar owes its angulated Form to Sea Salt; and the Crytals to other Salts: But there is no Warrant in Nature for this Judgment. Salts are acrid, and diolve in Water. Thee Foils have neither of thoe Qualities: And who hall tell us that the Property of forming itelf into regularly angulated Figures is peculiar to Salts? We have no Authority to believe it is wanting in Crytal, and Spar; and we have the Evidence of our Senes that they have it.

The ingenious and ingenuous Crontedt well oberves, thee Figures ought not to be acribed to Salts, till the Preence of uch Salts can be proved in them.

The calcarious Nature of Spar is of its Eence; and no Form, nor all the other Characters in the World, could contitute a Thing a Spar that wanted this. They all ferment with Acids, and they burn to Lime: Nor is this latter Quality equivocal, as ome would think, becaue by the Fire of a great Burning Glas, Spar vitrifies. This is not the Fire, when we peak of Lime; and it can be a Tet of nothing becaue all Things vitrify before it: That