several Colours out of Liquors, which have not any of them any such Colour,
nor indeed any discernable one at all; and whereas though our Author tells
us, that there was no Redness either in the Water, or the Leaves of
_Senna_, or the Oyl of Tartar; And though it be true, that the Predominant
Colour of the Leaves of _Senna_ be another than Red, yet we have try'd,
that by steeping that Plant a Night even in Cold water, it would afford a
very deep Yellow or Reddish Tincture without the help of the Oyl of Tartar,
which seems to do little more than assist the Water to extract more nimbly
a plenty of that Red Tincture, wherewith the Leaves of _Senna_ do of
themselves abound, and having taken off the Tincture of _Senna_, made only
with fair Water, before it grew to be Reddish, and Decanted it from the
Leaves, we could not perceive, that by dropping some Oyl of Tartar into it,
that Colour was considerable, though it were a little heightned into a
Redness; which might have been expected, if the particles of the Oyl did
eminently Co-operate, otherwise than we have expressed, to the production
of this Redness.

And as for the Experiment with Red-rose Leaves, the same thing may be
alleged, for we found that such Leaves by bare Infusion for a Night and Day
in fair Water, did afford us a Tincture bordering at least upon Redness,
and that Colour being conspicuous in the Leaves themselves, would not by
some seem so much to be produc'd as to be extracted by the affusion of Oyl
of Vitriol. And the Experiment try'd with the dry'd Leaves of Damask-roses
succeeded but imperfectly, but that is indeed observable to our Authors
purpose, that Oyl of Tartar will not perform in this Experiment what Oyl of
Vitriol doth; but because this last named Liquor is not so easily to be
had, give me leave to Advertise you, that the Experiment will succeed, if
instead of it you imploy _Aqua-fortis_. And though some Trials of our own
formerly made, and others easily deducible from what we have already
deliver'd, about the different Families and Operations of Salt, might