as we shall see anon, though weakn'd, so to work upon that Syrrup as to
change it into a Red or Reddish Colour. And to confirm that for which I
allege the former Experiment, I shall add this other, that having made a
very strong and high-colour'd Solution of Filings of Copper with Spirit of
Urine, though the _Menstruum_ seem'd Glutted with the Metall, because I put
in so much Filings that many of them remain'd for divers days Undissolv'd
at the Bottom, yet having put three or four Drops of Syrrup of Violets upon
White Paper, I found that the deep Blew Solution proportionably mingl'd
with this other Blew Liquor did not make a Blew mixture, but, as I
expected, a fair Green, upon the account of the Urinous Salt that was in
the _Menstruum_.

_EXPERIMENT XIX._

To shew the _Chymists_, that Colours may be made to Appear or Vanish, where
there intervenes no Accession or Change either of the Sulphureous, or the
Saline, or the Mercurial principle (as they speak) of Bodies: I shall not
make use of the Iris afforded by the Glass-prism, nor of the Colours to be
seen in a fair Morning in those drops of Dew that do in a convenient manner
Reflect and Refract the Beams of Light to the Eye; But I will rather mind
them of what they may observe in their own Laboratories, namely, that
divers, if not all, Chymical Essential Oyls, as also good Spirit of Wine,
being shaken till they have good store of Bubbles, those Bubbles will (if
attentively consider'd) appear adorn'd with various and lovely Colours,
which all immediately Vanish, upon the relapsing of the Liquor that affords
those Bubbles their Skins, into the rest of the Oyl, or Spirit of Wine, so
that a Colourless Liquor may be made in a trice to exhibit variety of
Colours, and may lose them in a moment without the Accession or Diminution
of any of its Hypostatical Principles. And, by the way, 'tis not unworthy
our notice, that some Bodies, as well Colourless, as Colour'd, by being