Among other Vegetables, which we thought likely to afford Exceptions to the
General Observation about the differing Changes of Colours produc'd by Acid
and Sulphureous Salts, we thought fit to make Trial upon the Flowers of
_Jasmin_, they being both White as to Colour, and esteem'd to be of a more
Oyly nature than other Flowers. Whereupon having taken the White parts only
of the Flowers, and rubb'd them somewhat hard with my Finger upon a piece
of clean Paper, it appear'd very little Discolour'd. Nor had Spirit of
Salt, wherewith I moisten'd one part of it, any considerable Operation upon
it. But Spirit of Urine, and somewhat more effectually a strong Alcalizate
Solution, did immediately turn the almost Colourless Paper moisten'd by the
Juice of the _Jasmin_, not as those Liquors are wont to do, when put upon
the Juices of other Flowers, of a good Green, but of a Deep, though
somewhat Greenish Yellow, which Experiment I did afterwards at several
times repeat with the like success. But it seems not that a great degree of
Unctuousness is necessary to the Production of the like Effects, for when
we try'd the Experiment with the Leaves of those purely White Flowers that
appear about the end of Winter, and are commonly call'd _Snow drops_, the
event, was not much unlike that, which, we have been newly mentioning.

_EXPERIMENT XXVIII._

Another sort of Instances to show, how much changes of Colour effected by
Salts, depend upon the particular Texture of the Colour'd Bodies, has been
afforded me by several _Yellow_ Flowers, and other Vegetables, as Mary-gold
Leaves, early Prim-roses, fresh Madder, &c. For being rubb'd upon White
Paper, till they imbued it with their Colour, I found not, that by the
addition of Alcalizate Liquors, nor yet by that of an Urinous Spirit, they
would be turn'd either Green or Red: nor did so Acid a Spirit, as that of
Salt, considerably alter their Colour, save that it seem'd a little to