sufficient both to justifie our Veracity, and to shew what we Intend; it
not being Essential to the Genuineness of a Colour to be Durable. For a
fading Leaf, that is ready to Rot, and moulder into Dust, may have as true
a Yellow, as a Wedge of Gold, which so obstinately resists both Time and
Fire. And the reason, why I take occasion from the former Experiment to
subjoyn this general Advertisement, is, that I have several times observ'd,
that the Mixture resulting from the Oyls of Vitriol, and of Anniseeds,
though it acquire a thicker consistence than either of the Ingredients had,
has quickly lost its Colour, turning in a very short time into a dirty
Gray, at least in the Superficial parts, where 'tis expos'd to the Air;
which last Circumstance I therefore mention, because that, though it seem
probable, that this Degeneration of Colours may oft times and in divers
cases proceed from the further Action of the Saline Corpuscles, and the
other Ingredients upon one another, yet in many cases much of the Quick
change of Colours seems ascribeable to the Air, as may be made probable by
several reasons: The first whereof may be fetcht from the newly recited
Example of the two Oyls; The next may be, that we have sometimes observ'd
long Window-Curtains of light Colours, to have that part of them, which was
expos'd to the Air, when the Window was open, of one Colour, and the lower
part, that was sheltred from the Air by the Wall, of another Colour: And
the third Argument may be fetch'd from divers Observations, both of others,
and our own; For of that Pigment so well known in Painters Shops, by the
name of _Turnsol_, our Industrious _Parkinson_, in the particular account
he gives of the Plant that bears it, tells us also, That _the Berries when
they are at their full Maturity, have within them between the outer Skin
and the inward Kirnel or Seed, a certain Juice or Moisture, which being
rubb'd upon Paper or Cloath, at the first appears of a fresh and lovely
Green Colour, but presently changeth into a kind of Blewish Purple, upon
the Cloath or Paper, and the same Cloath afterwards wet in Water, and wrung
forth, will Colour the Water into a Claret Wine Colour, and these_