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Experiments and Considerations Touching Colours (1664) by Robert Boyle
page 184 of 285 (64%)
For, I have found this Experiment to succeed in so many Various Berries,
Flowers, Blossoms, and other finer Parts of Vegetables, that neither my
Memory, nor my Leisure serves me to enumerate them. And it is somewhat
surprizing to see, by how Differingly-colour'd Flowers, or Blossoms, (for
example) the Paper being stain'd, will by an Acid Spirit be immediately
turn'd Red, and by any _Alcaly_ or any Urinous Spirit turn'd Green;
insomuch that ev'n the crush'd Blossoms of _Meserion_, (which I gather'd in
Winter and frosty Weather) and those of Pease, crush'd upon White Paper,
how remote soever their Colours be from Green, would in a moment pass into
a deep Degree of that Colour, upon the Touch of an Alcalizate Liquor. To
which let us add, That either of those new Pigments (if I may so call them)
may by the Affusion of enough of a contrary Liquor, be presently chang'd
from Red into Green, and from Green into Red, which Observation will hold
also in Syrrup of Violets, Juices of Blew-bottles, &c.

_Annotation._

After what I have formerly deliver'd to evince, That there are many
Instances, wherein new Colours are produc'd or acquir'd by Bodies, which
_Chymists_ are wont to think destitute of Salt, or to whose change of
Colours no new Accession of Saline Particles does appear to contribute, I
think we may safely enough acknowledge, that we have taken notice of so
many Changes made by the Intervention of Salts in the Colours of Mix'd
Bodies, that it has lessen'd our Wonder, That though _many Chymists_ are
wont to ascribe the Colours of Such Bodies to their Sulphureous, and _the
rest_ to their Mercurial Principle; yet _Paracelsus_ himself directs us in
the Indagation of Colours, to have an Eye principally upon Salts, as we
find in that passage of his, wherein he takes upon him to Oblige his
Readers much by Instructing them, of what things they are to expect the
Knowledge from each of the three distinct Principles of Bodies. _Alias_
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