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.
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