And First it seems that the favourers of the Chymicall Theories might have pitcht upon some more proper term, to express the Efficient of Blackness than _Sulphur adust_; for we know that _common Sulphur_, not only when Melted, but even when Sublim'd, does not grow Black by suffering the Action of the fire, but continues and ascends Yellow, and rather more than less White, than it was before its being expos'd to the fire. And if it be set on fire, as when we make that acid Liquor, that Chymists call _Oleum Sulphuris per campanam_, it affords very little Soot, and indeed the flame yeelds so little, that it will scarce in any degree Black a sheet of White Paper, held a pretty while over the flame and smoak of it, which is observed rather to Whiten than Infect linnen, and which does plainly make Red Roses grow very Pale, but not at all Black, as far as the Smoak is permitted to reach the leaves. And I can shew you of a sort of fixt Sulphur made by an Industrious Laborant of your acquaintance, who assur'd me that he was wont to keep it for divers weeks together night and day in a naked and Violent fire, almost like that of the Glass-house, and when, to satisfie my Curiosity, I made him take out a lump of it, though it were glowing hot (and yet not melted,) it did not, when I had suffered it to cool, appear Black, the true Colour of it being a true Red. I know it may be said, that _Chymists_ in the Opinion above recited mean the _Principle of Sulphur_, and not _common Sulphur_ which receives its name, not from its being _all_ perfectly of a Sulphureous Nature, but for that _plenty_ and _Predominancy_ of the Sulphureous Principle in it. But allowing this, 'tis easie to reply, that still according to this very Reason, torrifi'd Sulphur should afford more Blackness, than most other concretes, wherein that Principle is confess'd to be far less copious. Also when I have expos'd Camphire to the fire in Close Vessels, as Inflamable, and consequenly (according to the Chymists) as Sulphureous a Body as it is, I could not by such a degree of Heat, as brought it to Fusion, and made it Boyl in the glass, impress any thing of Blackness, or of any other Colour, than its own pure White, upon this Vegetable concrete. But what shall we say to Spirit of Wine, which being made by a Chymical Analysis of the Liquor that affords it, and being totally Inflamable, seems to have a full right to the title they give it of _Sulphur Vegetabile_, & yet this fluid Sulphur not only contracts not any degree of Blackness by being often so heated, as to be made to Boyl, but when it burns away with an Actual flame, I have not found that it would discolour a piece of White Paper held over it, with any discernable soot. Tin also, that wants not, according to the Chymists, a _Sulphur Joviale_, when throughly burned by the fire into a _Calx_, is not Black, but eminently White. And I lately noted to you out of _Bellonius_,