they able to make an imitation of any colour whatsoever:  Their Reds or deep Yellows, they can dilute by mixing pale Yellows with them, and deepen their pale by mixing deeper with them; for it is not with Opacous colours as it is with transparent, where by adding more Yellow to yellow, it is deepned, but in opacous diluted.  They can whiten any colour by mixing White with it, and darken any colour by mixing Black, or some dark and dirty colour.  And in a word, most of the colours, or colour’d bodies they use in Limning and Painting, are such, as though mixt with any other of their colours, they preserve their own hue, and by being in such very smal parts dispers’d through the other colour’d bodies, they both, or altogether represent to the eye a compositum of all; the eye being unable, by reason of their smalness, to distinguish the peculiarly colour’d particles, but receives them as one intire compositum:  whereas in many of these, the Microscope very easily distinguishes each of the compounding colours distinct, and exhibiting its own colour.

Thus have I by gently mixing Vermilion and Bise dry, produc’d a very fine Purple, or mixt colour, but looking on it with the Microscope, I could easily distinguish both the Red and the Blue particles, which did not at all produce the Phantasm of Purple.

To summ up all therefore in a word, I have not yet found any solid colour’d body, that I have yet examin’d, perfectly opacous; but those that are least transparent are Metalline and Mineral bodies, whose particles generally, seeming either to be very small, or very much flaw’d, appear for the most part opacous, though there are very few of them that I have look’d on with a Microscope, that have not very plainly or circumstantially manifested themselves transparent.

And indeed, there seem to be so few bodies in the world that are in minimis opacous, that I think one may make it a rational Query, Whether there be any body absolutely thus opacous?  For I doubt not at all (and I have taken notice of very many circumstances that make me of this mind) that could we very much improve the Microscope, we might be able to see all those bodies very plainly transparent, which we now are fain onely to ghess at by circumstances.  Nay, the Object Glasses we yet make use of are such, that they make many transparent bodies to the eye, seem opacous through them, which if we widen the Aperture a little, and cast more light on the objects, and not charge the Glasses so deep, will again disclose their transparency.