most 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, A A, each of which has a spurious pulse preceding it, as B B, which makes a Blue, and another following it, as C C, 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 to 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 the refraction of the dissolvent be increas’d, and the refraction of the tinging particles not altered, then will the preceding spurious pulse be shortned or stopt, and not out-run the clear pulse so much; so that B B will become E E, and the Blue be diluted, whereas the other spurious pulse which follows will be made to lagg much more, and be further behind A A than before, and C C will become f f and so the Yellow or Red will be heightned.
A Saline liquor therefore, mixt with another ting’d liquor, may alter the colour of it several ways, either by altering the refraction of the liquor in which the colour swims: or secondly by varying the refraction of the coloured particles, by uniting more intimately either with some particular corpuscles of the tinging body, or with all of them, according as it has a congruity to some more especially, or to all alike: or thirdly, by uniting and interweaving it self with some other body that is already joyn’d with the tinging particles, with which substance it may have a congruity, though it have very little with the particles themselves; or fourthly, it may alter the colour of a ting’d liquor by dis-joyning certain particles which were before united with the tinging particles, which though they were somewhat congruous to these particles, have yet a greater congruity with the newly infus'd Saline menstruum. It may likewise alter the colour by further dissolving the tinging substance into smaller and smaller particles, and so diluting the colour; or by uniting feveral particles together as in precipitations, and so deepning it, and some such other ways, which many experiments and companions of differing trials together, might easily inform one of.
From these Principles applied, may be made out all the varieties of colours observable, either in liquors, or any other ting’d bodies, with great ease, and I hope intelligible enough, there being nothing in the notion of colour, or in the suppos’d production, but is very conceivable, and may be possible.
The greatest difficulty that I find against this Hypothesis, is, that there seem to be more distinct colours then two, that is, then Yellow and Blue. This Objection is grounded on this reason, that there are several Reds which diluted, make not a Saffron or pale Yellow, and therefore Red, or Scarlet seems to be a third colour distinct from a deep degree of Yellow.
To which I answer, that Saffron affords us a deep Scarlet tincture, which may be diluted into as pale a Yellow as any, either by making a weak so-
