another, according as their Ponderousness makes them Swim or Sink. For 'tis Observable, that though Oyl or Liquid Sulphur be one of the Elements Separated by this Fiery _Analysis_, yet the Heat which Accidentally Unites the Particles of the other Volatile Principles, has not alwayes the same Operation on this, there being divers Bodies which Yield Two Oyls, whereof the One sinks to the Bottom of that Spirit on which the other Swims; as I can shew You in some Oyls of the same Deers Blood, which are yet by Me: Nay I can shew you Two Oyls carefully made of the same Parcel of Humane Blood, which not only Differ extreamly in Colour, but Swim upon one another without Mixture, and if by Agitation Confounded will of themselves Divorce again. And that the Fire doth oftentimes divide Bodies, upon the account that some of their Parts are more Fixt, and some more Volatile, how far soever either of these Two may be from a pure Elementary Nature is Obvious enough, if Men would but heed it in the Burning of Wood, which the Fire Dissipates into Smoake and Ashes: For not only the latter of these is Confessedly made up of two such Differing Bodies as Earth and Salt; but the Former being condens'd into that Soot which adheres to our Chimneys, Discovers it self to Contain both Salt and Oyl, and Spirit and Earth, (and some Portion of Phlegme too) which being, all almost, Equally Volatile to that Degree of Fire which Forces them up, (the more Volatile Parts Helping perhaps, as well as the Urgency of the Fire, to carry up the more Fixt ones, as I have often Try'd in Dulcify'd _Colcothar_, Sublim'd by _Sal Armoniack_ Blended with it) are carried Up together, but may afterwards be Separated by other Degrees of Fire, whose orderly Gradation allowes the Disparity of their Volatileness to Discover it self. Besides, if Differing Bodies United into one Mass be both sufficiently Fixt, the Fire finding no Parts Volatile enough to be Expell'd or carried up, makes no Separation at all; as may appear by a Mixture of Colliquated Silver and Gold, whose Component Metals may be easily Sever'd by _Aqua Fortis_, or _Aqua Regis_ (according to the Predominancy of the Silver or the Gold) but in the Fire alone, though vehement, the Metals remain unsever'd, the Fire only dividing the Body into smaller Particles (whose Littlenesse may be argu'd from their Fluidity) in which either the little nimble Atoms of Fire, or its brisk and numberless strokes upon the Vessels, hinder Rest and Continuity, without any Sequestration of Elementary Principles. Moreover, the Fire sometimes does not Separate, so much as Unite, Bodies of a differing Nature; provided they be of an almost resembling Fixedness, and have in the Figure of their Parts an Aptness to Coalition, as we see in the making of many Plaisters, Oyntments, &c. And in such Metalline Mixtures as that made by Melting together two parts of clean Brass with one of pure Copper, of which some Ingenious Trades-men cast such curious