Blues may be diluted, as Smalt and Bise; and Masticut, which is Yellow, may be made more faint: And even Vermilion it self may, by too much grinding, be brought to the colour of Red-lead, which is but an Orange colour, which is confest by all to be very much upon the Yellow. Now, though perhaps somewhat of this diluting of Vermilion by overmuch grinding may be attributed to the Grindstone, or muller, for that some of their parts may be worn off and mixt with the colour, yet there seems not very much, for I have done it on a Serpentine-stone with a muller made of a Pebble, and yet observ'd the same effect follow.
And secondly, as to the other of these operations on colours, that is, the deepning of them, Limners and Painters colours are for the most part also uncapable. For they being for the most part opacous; and that opacousness, as I said before, proceeding from the particles, being very much flaw'd, unless we were able to joyn and re-unite those flaw'd particles again into one piece, we shall not be able to deepen the colour, which since we are unable to do with most of the colours which are by Painters accounted opacous, we are therefore unable to deepen them by adding more of the same kind.
But because all those opacous colours have two kinds of beams or Rays reflected from them, that is, Rays unting'd, which are onely reflected from the outward surface, without at all penetrating of the body, and ting'd Rays which are reflected from the inward surfaces or flaws after they have suffer'd a two-fold refraction; and because that transparent liquors mixt with such corpuscles, do, for the most part, take off the former kind of reflection; therefore these colours mixt with Water or Oyl, appear much deeper than when dry, for most part of that white reflection from the outward surface is remov'd. Nay, some of these colours are very much deepned by the mixture with some transparent liquor, and that because they may perhaps get between those two flaws, and so consequently joyn two or more of those flaw'd pieces together; but this happens but in a very few.
Now, to shew that all this is not gratis dictum, I shall set down some Experiments which do manifest these things to be probable and likely, which I have here deliver'd.
For, first, if you take any ting'd liquor whatsoever, especially if it be pretty deeply ting'd, and by any means work it into a froth, the congeries of that froth shall seem an opacous body, and appear of the same colour, but much whiter than that of the liquor out of which it is made. For the abundance of reflections of the Rays against those surfaces of the bubbles of which the froth consists, does so often rebound the Rays backwards, that little or no light can pass through, and consequently the froth appears opacous.
Again, if to any of these ting'd liquors that will endure the boiling there be added a small quantity of fine flower (the parts of which through the Microscope are plainly enough to be perceiv'd to consist of transparent corpuscles) and suffer'd to boyl till it thicken the liquor, the mass of the liquor will appear opacous, and ting'd with the same colour, but very much whiten'd.
