I time to examine several particulars requisite to the demonstration of it,
I might prove it more than probable, for all the experiments about the
changes and mixings of colours related in the Treatise of Colours,
published by the _Incomparable_ Mr. _Boyle_, and multitudes of others which
I have observ'd, do so easily and naturally flow from those principles,
that I am very apt to think it probable, that they own their production to
no other _secundary_ cause: As to instance in two or three experiments. In
the twentieth Experiment, this _Noble Authour_ has shewn that the deep
_bluish purple-colour_ of _Violets_, may be turn'd into a _Green_, by
_Alcalizate Salts_, and to a _Red_ by acid; that is, a _Purple_ consists of
two colours, a deep _Red_, and a deep _Blue_; when the _Blue_ is diluted,
or altered, or destroy'd by _acid Salts_, the _Red_ becomes predominant,
but when the _Red_ is diluted by _Alcalizate_, and the _Blue_ heightned,
there is generated a _Green_; for of a _Red_ diluted, is made a _Yellow_,
and _Yellow_ and _Blue_ make a _Green_.

Now, because the _spurious_ pulses which cause a _Red_ and a _Blue_, do the
one follow the clear pulse, and the other precede it, it usually follows,
that those _Saline_ refracting bodies which do _dilute_ the colour of the
one, do deepen that of the other. And this will be made manifest by almost
all kinds of _Purples_, and many sorts of _Greens_, both these colours
consisting of mixt colours; for if we suppose A and A in the ninth Figure,
to represent two pulses of clear light, which follow each other at a
convenient distance, AA, each of which has a _spurious_ pulse preceding it,
as BB, which makes a _Blue_, and another following it, as CC, which makes a
_Red_, the one caus'd by tinging particles that have a greater refraction,
the other by others that have a less refracting quality then the liquor or
_Menstruum_ in which these are dissolv'd, whatsoever liquor does so alter
the refraction of the one, without altering that of the other part of the
ting'd liquor, must needs very much alter the colour of the liquor; for if