I referr (sayes _Carneades_) to another Occasion, the Use that may be made of these Narratives towards the explicating the Nature of Metalls; and that of Fixtness, Malleableness, and some other Qualities conspicuous in them. And in the mean time, this I may at present deduce from these Observations, That 'tis not very probable, that, whensoever a Mineral, or even a Metall, is to be Generated in the Bowels of the Earth, Nature needs to have at hand both Salt, and Sulphur, and Mercury to Compound it of; for, not to urge that the two last Relations seem less to favour the Chymists than _Aristotle_, who would have Metals Generated of certain _Halitus_ or steams, the foremention'd Observations together, make it seem more Likely that the mineral Earths or those Metalline steams (wherewith probably such Earths are plentifully imbu'd) do contain in them some seminal Rudiment, or some thing Equivalent thereunto; by whose plastick power the rest of the matter, though perhaps Terrestrial and heavy, is in Tract of time fashion'd into this or That metalline Ore; almost as I formerly noted, that fair water was by the seminal Principle of Mint, Pompions, and other Vegetables, contriv'd into Bodies answerable to such Seeds. And that such Alterations of Terrestrial matter are not impossible, seems evident from that notable Practice of the Boylers of Salt-Petre, who unanimously observe, as well here in _England_ as in other Countries; That if an Earth pregnant with Nitre be depriv'd, by the affusion of water, of all its true and dissoluble Salt, yet the Earth will after some years yield them Salt-Petre again; For which reason some of the eminent and skillfullest of them keep it in heaps as a perpetual Mine of Salt Petre; whence it may appear, that the Seminal Principle of Nitre latent in the Earth does by degrees Transforme the neighbouring matter into a Nitrous Body; for though I deny that some Volatile Nitre may by such Earths be attracted (as they speak) out of the Air, yet that the innermost parts of such great heaps that lye so remote from the Air should borrow from it all the Nitre they abound with, is not probable, for other reasons besides the remoteness of the Air, though I have not the Leasure to mention them. And I remember, that a person of Great Credit, and well acquainted with the wayes of making Vitriol, affirm'd to me, that he had observ'd, that a kind of mineral which abounds in that Salt, being kept within Doors and not expos'd (as is usual) to the free Air and Rains, did of it self in no very long time turn into Vitriol, not only in the outward or superficial, but even in the internal and most Central parts.