this last reflection does not return a quarter so many Rays, as that which
is made from the surface of the air, as I have certainly found by a
multitude of Observations and Experiments.

The whiteness of _Linnen_, _Paper_, _Silk_, &c. proceeds much from the same
reason, as the _Microscope_ will easily discover; for the Paper is made up
of an abundance of _pellucid_ bodies, which afford a very plentifull
reflection from within, that is, from the concave surface of the air
contiguous to its component particles; wherefore by the affusion of Water,
Oyl, Tallow, Turpentine, &c. all those reflections are made more faint, and
the beams of light are suffer'd to traject & run through the Paper more
freely.

Hence further we may learn the reason of the whiteness of many bodies, and
by what means they maybe in part made _pellucid_: As white Marble for
instance, for this body is composed of a _pellucid_ body exceedingly
flaw'd, that is, there are abundance of thin, and very fine cracks or
chinks amongst the multitude of particles of the body, that contain in them
small parcels of air, which do so _re-percuss_ and drive back the
penetrating beams, that they cannot enter very deep within that body; which
the _Microscope_ does plainly inform us to be made up of a _Congeries_ of
_pellucid_ particles. And I further found it somewhat more evidently by
some attempts I made towards the making transparent Marble, for by heating
the Stone a little, and baking it in Oyl, Turpentine, Oyl of Turpentine,
&c., I found that I was able to see much deeper into the body of Marble
then before; and one trial, which was not with an unctuous substance,
succeeded better than the rest, of which, when I have a better opportunity,
I shall make further trial.

This also gives us a probable reason of the so much admired _Phænomena_, of