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 compounded, so are the _sensations_, and consequently the
_phantasms_ of colours _diversified_.
To proceed therefore; I suppose, that all transparent colour'd bodies,
whether fluid or solid, do consist at least of two parts, or two kinds of
substances, the one of a substance of a somewhat differing _refraction_
from the other. That one of these substances which may be call'd the
_tinging_ substance, does consist of distinct parts, or particles of a
determinate bigness which are _disseminated_, or dispers'd all over the
other: That these particles, if the body be equally and uniformly colour'd,
are evenly rang'd and dispers'd over the other contiguous body; That where
the body is deepest ting'd, there these particles are rang'd thickest, and
where 'tis but faintly ting'd, they are rang'd much thinner, but uniformly.
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