Page:Theophrastus - History of Stones - Hill (1774).djvu/314

 That is the extreme Force of Fire: And the ultimate Effect of Fire on all Bodies is Vitrification.

Linnæus ays, the Spar he calls Natro-patoum, carce does effervece with Acids: And it may be added, that the Particles of that Spar are, carcely at all rhombic: Spar and Crytal are mixt in thoe Bodies; and they have mixt Qualities; but till as there is ome Spar, there is ome Effervecence.

'Tis vain to give the Forms of Spar to Natrum; for we not only find no Natrum there, but different Spars have Forms of different Salts; and the great Patron of the Salt Sytem allows, that fome of them affect the various angulated Figures of Alum, Sea-Salt, Vitriol, and the reft. 'Tis true, they reemble thoe Forms; but they have not thoe Forms exactly: Nor is either of thee, or any other Salt whatever, to be found exiting in any of them.

But whither will not the Wind of Theory blow even the teadiet Judgments? The foremot of the Writers, who favour this Sytem, becaue there are in Spars certain Forms that do not, agree with thoe of any known Salt, fancies for the Formation of thee that there exit Salts, not otherwie known to us, but by this Operation. When Theory can reach this Heighth, it may do what it pleaes: To create Caues, becaue we ee Effects that eem to us to require them, is to make all Things eay; and at the cheapet Rate. If