But, proceeds Carneades, If it had not been to afford You some hints concerning the Origine of Metals, I need not have deduc’d any thing from these Observations; It not being necessary to the Validity of my Argument that my Deductions from them should be irrefragable, because my Adversaries the Aristotelians and Vulgar Chymists do not, I presume, know any better then I, a priori, of what ingredients Nature compounds Metals and Minerals. For their Argument to prove that those Bodies are made up of such Principles, is drawn a posteriori; I mean from this, that upon the Analysis of Mineral bodies they are resolv’d into those differing substances. That we may therefore examine this Argument, Let us proceed to consider what can be alledg’d in behalf of the Elements from the Resolutions of Bodies by the fire; which you remember was the second Tophick whence I told you the Arguments of my Adversaries were desum’d.
And that I may first dispatch what I have to say concerning Minerals, I will begin the remaining part of my discourse with considering how the fire divides them.
And first, I have partly noted above, that though Chymists pretend from some to draw salt, from others running Mercury, and from others a Sulphur; Yet they have not hitherto taught us by any way in us among them to separate any one principle, whether Salt, Sulphur, or Mercury, from all sorts of Minerals without exception. And thence I may be allow’d to conclude that there is not any of the Elements that is an Ingredient of all Bodies, since there are some of which it is not so.