The First Part.

any separation of Heterogeneities, but only a comminution of Parts, those that rise first being Homogeneal with the others, though subdivided into smaller Particles: whence Sublimations have been stiled, The Pestles of the Chymists. But not here to mention what I elsewhere take notice of, concerning common Brimstone once or twice sublim’d, that expos’d to a moderate Fire in Subliming-Pots, it rises all into dry, and almost tastless, Flowers; Whereas being expos’d to a naked Fire it affords store of a Saline and Fretting Liquor: Not to mention this, I say, I will further observe to you, that as it is considerable in the Analysis of mixt Bodies, whether the Fire act on them when they are expos’d to the open Air, or shut up in close Vessels, so is the degree of Fire by which the Analysis is attempted of no small moment. For a milde Balneum will sever unfermented Blood (for Instance) but into Phlegme and Caput mortuum, the later whereof (which I have sometimes had) hard, brittle, and of divers Colours, (transparent almost like Tortoise-shell) press’d by a good Fire in a Retort yields a Spirit, an Oyl or two, and a volatile Salt, besides a Caput mortuum. It may be also pertinent to our present Designe, to take notice of what happens in the making and distilling of Sope; for by one degree of Fire the Salt, the Water and the Oyl or Grease, whereof that factitious Concrete is made up, being boyl’d up together are easily brought to mingle and incorporate into one Mass; but by another and further degree of Heat the same Mass may be again divided into an oleagenous, an aqueous, a Saline, and an Earthy part. And so we may observe that impure Silver and Lead being expos’d together to a moderate Fire, will thereby be colliquated into one Mass, and mingle per minima, as they speak, whereas a much vehementer Fire will drive or carry off the baser Metals (I mean the Lead, and the Copper or other Alloy) from the Silver, though not, for ought appears, separate them from one another. Besides, when a Vegetable abounding in fixt Salt is analyz’d by a naked Fire, as one degree of Heat will reduce it into Ashes, (as the Chymists themselves teach us) so, by only a further degree of Fire, those Ashes may be vitrified and turn’d into Glass. I will not stay to examine how far a