ht reflected from the Water below
look'd green. For thence it may be gather'd, that the Sea-Water reflects
back the violet and blue-making Rays most easily, and lets the
red-making Rays pass most freely and copiously to great Depths. For
thereby the Sun's direct Light at all great Depths, by reason of the
predominating red-making Rays, must appear red; and the greater the
Depth is, the fuller and intenser must that red be. And at such Depths
as the violet-making Rays scarce penetrate unto, the blue-making,
green-making, and yellow-making Rays being reflected from below more
copiously than the red-making ones, must compound a green.

Now, if there be two Liquors of full Colours, suppose a red and blue,
and both of them so thick as suffices to make their Colours sufficiently
full; though either Liquor be sufficiently transparent apart, yet will
you not be able to see through both together. For, if only the
red-making Rays pass through one Liquor, and only the blue-making
through the other, no Rays can pass through both. This Mr. _Hook_ tried
casually with Glass Wedges filled with red and blue Liquors, and was
surprized at the unexpected Event, the reason of it being then unknown;
which makes me trust the more to his Experiment, though I have not tried
it my self. But he that would repeat it, must take care the Liquors be
of very good and full Colours.

Now, whilst Bodies become coloured by reflecting or transmitting this or
that sort of Rays more copiously than the rest, it is to be conceived
that they stop and stifle in themselves the Rays which they do not
reflect or transmit. For, if Gold be foliated and held between your Eye
and the Light, the Light looks of a greenish blue, and therefore massy
Gold lets into its Body the blue-making Rays to be reflected to and fro
within it till they be stopp'd and stifled, whilst it reflects the
yellow-making outwards, and thereby looks yellow. And much after the
same manner that Leaf Gold is yellow by reflected, and blue by
transmitted Light, and massy Gold is yellow in all Positions of the Eye;
there are some Liquors, as the Tincture of _Lignum Nephriticum_, and
some sorts of Glass which transmit one sort of Light most copiously, and
reflect another sort, and thereby look of several Colours, according to
the Position of the Eye to the Light. But, if these Liquors or Glasses
were so thick and massy that no Light could get through them, I question
not but they would like all other