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We ſee the Way Art imitates it beſt, is by the Cryſtals of a Liquor in which Lime and Sulphur have been boiled. Sulphur is thus diſcloſed on the calcining of Spar; and for the other Ingredient, Lime, we cannot be at a Loſs; ſince it has been obſerved, no Spar is ever produced in Cracks of any Rocks, except thoſe of Limeſtone: Nay, and what may ſtrengthen this Opinion, the Lime of Spar is weaker than that of Limeſtone, which a little Sulphur may cauſe. All this, is but Conjecture; and is delivered as ſuch, and no other; but yet it reſts on the Teſtimonies of the Senſes; not on the Flights of the Imagination: And it is by Conjecture, in theſe dark and difficult Reſearches, we muſt arrive at Truth.
I claim no better Authority for many of the particular Obſervations here, than for this general one; they are indeed all founded on Examination, and Experiments, now made on the Occaſion; but they are Examinations and Experiments made only on the Bodies in my own ſcanty Store: I invite, I ſollicit, and intreat with my beſt Earneſtneſs, others to repeat them on their own. If they anſwer as in mine, the Doctrines are eſtabliſhed; if they differ, there is no one in the World to whom that Truth will be more welcome than to myſelf. To equivocate about an Error, is pitiful: to attempt to juſtify it, is diſingenuous: No Man ſhould be aſhamed of ſetting right his own Miſtakes (eſpecially in
