fluid or solid bodies,
whether in thick or thin, whether transparent, or seemingly opacous, as I
shall in the next Observation further endeavour to shew. And secondly,
because this being one of the two ornaments of all bodies discoverable by
the sight, whether looked on with, or without a _Microscope_, it seem'd to
deserve (somewhere in this Tract, which contains a description of the
Figure and Colour of some minute bodies) to be somewhat the more intimately
enquir'd into.

* * * * *

Observ. X. _Of _Metalline_, and other real Colours._

Having in the former Discourse, from the Fundamental cause of Colour, made
it probable, that there are but two Colours, and shewn, that the _Phantasm_
of Colour is caus'd by the sensation of the _oblique_ or uneven pulse of
Light which is capable of no more varieties than two that arise from the
two sides of the _oblique_ pulse, though each of those be capable of
infinite gradations or degrees (each of them beginning from _White_, and
ending the one in the deepest _Scarlet_ or _Yellow_, the other in the
deepest _Blue_) I shall in this _Section_ set down some Observations which
I have made of other colours, such as _Metalline_ powders tinging or
colour'd bodies and several kinds of tinctures or ting'd liquors, all
which, together with those I treated of in the former Observation will, I
suppose, comprise the several subjects in which colour is observ'd to be
inherent, and the several manners by which it _inheres_, or is apparent in
them. And here I shall endeavour to shew by what composition all kind of
compound colours are made, and how there is no colour in the world but may
be made from the various degrees of these two colours, together with the
intermixtures of _Black_ and _White_.

And this being so, as I shall anon shew, it seems an evident argument to
me, that all colours whatsoever, whether in fluid or solid, whether in very
transparent or seemingly _opacous_, have the same efficient cause, to wit,
some kind of _refraction_ whereby the Rays that proceed from such bodies,
have their pulse _obliquated_ or confus'd in the manner I explicated in the
former _Section_; that is, a _Red_ is caus'd by a duplicated or confus'd
pulse, whose strongest pulse precedes, and a weaker follows: and a _Blue_
is caus'd by a confus'd pulse, where the weaker pulse precedes, and the
stronger follows. And according as these are, more or less, or variously
mixt and co