The way, _Pyrophilus,_ of producing Whiteness by Chymical Præcipitations is very well worth our observing, for thereby Bodyes of very Differing Colours as well as Natures, though dissolv'd in Several Liquors, are all brought into _Calces_ or Powders that are White. Thus we find that not only Crabs-eyes, that are of themselves White, and Pearls that are almost so, but _Coral_ and _Minium_ that are Red, being dissolv'd in Spirit of Vinegar, may be uniformly Præcipitated by Oyl of _Tartar_ into White Powders. Thus Silver and Tin separately dissolv'd in _Aqua Fortis_, will the one Præcipitate it self, and the other be Præcipitated by common Salt-water into a White _Calx_, and so will Crude Lead and Quicksilver first dissolv'd likewise in _Aqua Fortis_. The like _Calx_ will be afforded as I have try'd by a Solution of that shining Mineral Tinglass dissolv'd in _Aqua Fortis_, and Præcipitated out of it; and divers of these _Calces_ may be made at least as Fair and White, if not better Colour'd, if instead of Oyl of _Tartar_ they were Præcipitated with Oyl of _Vitriol_, or with another Liquor I could Name. Nay, that Black Mineral _Antimony_ it self, being reduc'd by and with the Salts that concurr to the Composition of common Sublimate, into that Cleer though Unctuous Liquor that Chymists commonly call Rectifi'd Butter of _Antimony_, will by the bare affusion of store of Fair Water be struck down into that Snow-white Powder, which when the adhering Saltness is well wash'd off, Chymists are pleas'd to call _Mercurius Vitæ_, though the like Powder may be made of _Antimony_, without the addition of any _Mercury_ at all. And this Lactescence if I may so call it, does also commonly ensue when Spirit of Wine, being Impregnated with those parts of Gums or other Vegetable Concretions, that are suppos'd to abound with Sulphureous Corpuscles, fair Water is suddenly pour'd upon the Tincture or Solution. And I remember that very lately I did, for Tryal sake, on a Tincture of _Benjamin_ drawn with Spirit of Wine, and brought to be as Red as Blood, pour some fair Water, which presently mingling with the Liquor, immediately turn'd the whole Mixture White. But if such Seeming Milks be suffer'd to stand unstirr'd for a convenient while, they are wont to let fall to the bottome a Resinous Substance, which the Spirit of Wine Diluted and Weakned by the Water pour'd into it was unable to support any longer. And something of Kin to this change of Colour in Vegetables is that, which Chymists are wont to observe upon the pouring of Acid Spirits upon the Red Solution of _Sulphur_, dissolv'd in an Infusion of Pot-ashes, or in some other sharp _Lixivium_, the Præcipitated _Sulphur_ before it subsides, immediately turning the Red Liquor into a White one. And other Examples might be added of this way of producing Whiteness in Bodyes by Præcipitating them out of the Liquors wherein they have been Dissolv'd; but