because several of these Rays that go to the constitution of these pulses will be slugged or stopped by the tinging particles E, F, G, H; therefore there shall be secundary and weak pulse that shall follow the Ray, namely P P which will be the weaker: first, because it has suffer'd many refractions in the impeding body; next, for that the Rays will be a little dispers'd or confus'd by reason of the refraction in each of the particles, whether round or angular; and this will be more evident, if we a little more closely examine any one particular tinging Globule.
Suppose we therefore A B in the eighth Figure of the sixth Scheme, to represent a tinging Globule or particle which has a greater refraction than the liquor in which it is contain'd: Let C D be a part of the pulse of light which is propagated through the containing medium; this pulse will be a little stopt or impeded by the Globule, and so by that time the pulse is past to E F that part of it which has been impeded by passing through the Globule, will get but to L M, and so that pulse which has been propagated through the Globule, to wit, L M, N O, P Q, will always come behind the pulses E F, G H, I K, &c.
Next, by reason of the greater impediment in A B, and its Globular Figure, the Rays that pass through it will be dispers'd, and very much scatter'd. Whence C A and D B which before went direct and parallel, will after the refraction in A B, diverge and spread by A P, and B Q; so that as the Rays do meet with more and more of these tinging particles in their way, by so much the more will the pulse of light further lagg behind the clearer pulse, or that which has fewer refractions, and thence the deeper will the colour be, and the fainter the light that is trajected through it; for not onely many Rays are reflected from the surfaces of A B, but those Rays that get through it are very much disordered.
By this Hypothesis there is no one experiment of colour that I have yet met with, but may be, I conceive, very rationably solv'd, and perhaps, had 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 al-
