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 [Errata: another] _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 meere Chymist might on this occasion demand, If it be lawful for an _Aristotelian_ to make Ashes, (which he mistakes for meere Earth) pass for an Element, because by one degree of Fire it may be produc'd, why a Chymist may not upon the like Principle argue, that Glass is one of the Elements of many Bodies, because that also may be obtain'd from them, barely by the Fire? I will not, I say, lose time to examine this, but observe, that by a Method of applying the Fire, such similar Bodies may be obtain'd from a Concrete, as Chymists have not been able to separate; either by barely burning it in an open Fire, or by barely distilling it in close Vessels. For to me it seems very considerable, and I wonder that men have taken so little notice of it, that I have not by any of the common wayes of Distillation in close Vessels, seen any separation made of such a volatile Salt as is afforded us by Wood, when that is first by an open Fire divided into Ashes and Soot, and that Soot is afterwards plac'd in a strong Retort, and compell'd by an urgent Fire to part with its Spirit, Oyl and Salt; for though I dare not peremptorily deny, that in the Liquors of _Guajacum_ and other Woods distill'd in Retorts after the common manner, there may be Saline parts, which by reason of the Analogy may pretend to the name of some kinde of volatile Salts; yet questionless there is a great