attempt to shew the usefulness of Chymical Experiments to Contemplative Philosophers, will give those that shall read them other thoughts of me: & I had a design (but wanted opportunity) to publish with these Papers an Essay I have lying by me, the greater part of which is Apologetical for one sort of Chymists. And at least, as for those that know me, I hope the pain I have taken in the fire will both convince them, that I am far from being an Enemy to the Chymists Art, (though I am no friend to many that disgrace it by professing it,) and perswade them to believe me when I declare that I distinguish betwixt those Chymists that are either Cheats, or but Laborants, and the true_ Adepti; _By whom, could I enjoy their Conversation, I would both willingly and thankfully be instructed; especially concerning the Nature and Generation of Metals: And possibly, those that know how little I have remitted of my former addictedness to make Chymical Experiments, will easily believe, that one of the chief Designes of this Sceptical Discourse was, not so much to discredit Chymistry, as to give an occasion and a kind of necessity to the more knowing Artists to lay aside a little of their over-great Reservedness, & either explicate or prove the Chymical Theory better than ordinary Chymists have done, or by enriching us with some of their nobler secrets to evince that Their art is able to make amends even for the deficiencies of their Theory: And thus much I shall here make bold to add, that we shall much undervalue Chymistry, if we imagine, that it cannot teach us things farr more useful, not only to Physick but to Philosophy, than those that are hitherto known to vulgar Chymists. And yet as for inferiour Spagyrists themselves, they have by their labours deserv'd so well of the Common-wealth of Learning, that methinks 'tis Pity they should ever misse the Truth which they have so industriously sought. And though I be no Admirer of the Theorical Part of their Art, yet my conjectures will much deceive me, if the Practical Part be not much more cultivated than hitherto it has been, and do not both employ Philosophy and Philosophers, and help to make men such. Nor would I that have been diverted by other Studies as well as affairs, be thought to pretend being a profound Spagyrist, by finding so many faults in the Doctrine wherein the Generality of Chymists scruples not to Acquiesce: For besides that 'tis most commonly far easier to frame Objections against any propos'd_ Hypothesis, _than to propose an_ Hypothesis _not lyable to Objections (besides this I say) 'tis no such great matter, if whereas Beginners in Chymistry are commonly at once imbu'd with the Theory and Operations of their profession, I who had the good Fortune to Learn the Operations from illiterate Persons, upon whose credit I was not Tempted to take up any opinion about them, should consider things with lesse prejudice, and consequently with