_EXPERIMENT XV._
And now, _Pyrophilus_, it will not be improper for us to take some notice
of an Opinion touching the cause of Blackness, which I judged it not so
seasonable to Question, till I I had set down some of the Experiments, that
might justifie my dissent from it. You know that of late divers Learned
Men, having adopted the three Hypostatical Principles, besides other
Notions of the Chymists, are very inclinable to reduce all Qualities of
Bodies to one or other of those three Principles, and Particularly assign
for the cause of Blackness the Sootie steam of _adust_ or _torrifi'd
Sulphur_. But I hope that what we have deliver'd above to countenance the
Opinion we have propos'd about the Cause of Blackness, will so easily
supply you with several Particulars that may be made use of against this
Opinion, that I shall now represent to You but two things concerning it.
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.
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