the mixing and tempering these colours together, are 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.