reflection of the light from the surface of the air within the Bubbles, and very little to the reflection from the surface of the Water it self: for 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 the Oculus Mundi, an Oval stone, which commonly looks like white Alabaster, but being laid a certain time in Water, it grows pellucid, and transparent, and being suffer'd to lie again dry, it by degrees loses that transparency, and becomes white as before. For the Stone being of a hollow spongie nature, has in the first and last of these appearances, all those pores fill'd with the obtunding and reflecting air; whereas in the second, all those pores are fill'd with a medium that has much the same refraction with the particles of the Stone, and therefore those two being contiguous, make, as 'twere, one continued medium, of which more is said in the 15. Observation.
There are a multitude of other Phænomena, that are produc'd from this same Principle, which as it has not been taken notice of by any yet that I know, so I think, upon more diligent observation, will it not be found the least considerable. But I have here onely time to hint Hypotheses, and not to prosecute them so fully as I could wish; many of them having a vast extent in the production of a multitude of Phænomena, which have been by others, either not attempted to be explain'd, or else attributed to some other cause than what I have assign'd, and perhaps than the right; and therefore I shall leave this to the prosecution of such as have more leisure:
