84 
A 
4 
MrcROGRAPHYA. 
reflection of the light from the furface of the air within the Bubbles,and_ 
very little tothe reflection from the furface of the Water it felf: for this. 
laft refle@ion does not return a Quarter fo many Rays, as that which is 
made from the furface of the air,as1 have certainly found by a multitude: | 
of Obfervations and Experiments. ee ‘ 
The whitenefS of Linnen, Paper; silk, &c. proceeds much from the 
fame reafon, asthe Aficrofcope will eafily difcover’ for the Paper is made* 
up of an abundance of peM/ucid bodies, which afford a very plentifull re- 
flection from within, that is, from the concave furface of the air contigu- 
ous to its component particles ; wherefore by the affifion of Water, Oyl, 
Tallow, Turpentine,@c."all thofe reflections are made more faint,and the 
beams of light are faffer'd to trajeét & run through the Paper more freely. 
~ Hence further we may learn the reafon of the whitenefs of many bo- 
dies, and by what means they’ may be in part made pe//xcid: As white 
Marble for inftance, for this body is compofed of a pelluctd body ex- 
ecedingly flaw’d, that is, there are abundance of thin, and very fine 
cracks or chinks amongft the multitude of particles of the body,that con- 
tain in them {mall parcels of air,which do {o re-perc#{fand drive back the 
penetrating beams, that ‘they cannot enter very deep within that body, 
which the Microfcope does plainly inform us to be made up of a Comgeries 
of pel/uctd particles. And I further found it fomewhat more evidently by — 
fome attempts I made towards the making tranfparent Marble, for by 
heating the Stone a little, and foaking it in Oy], Turpentine, Oy! of Tur- 
| pean. I found that I was able to fee much deeper into the body of © 
arblethen before ; and one trial, which was not with an unctuous fub- 
ftance,fucceeded better than the reft, of which, whenI have a better op- 
portunity, I fhall make further trial.-- AES SID LER IW (0 51 
This alfo gives us a probable reafon of the fo much admired Pheno- 
mena of the Oculus Mundi, an Oval {tone, which commonly looks like 
white Alabafter, but being laid a certain time in Water, it grows pel/ucid, 
and tran{parent, and being fuffer'd to lie again dry, it by degrees lofes 
that tran{fparency, and becomes white as before. For the Stone being of 
a hollow fpongie nature, has in the firft and laft of thefe appearances, all 
thofe pores fill'd with the obtunding and reflecting air; whereas’ in the 
fecond, all thofe pores are fill’d with a medium that has much the fame 
refraction with the particles of the Stone, and therefore thofetwobeing 
contiguous, make,as twere, one continued medium, of which more isfaid 
in the 15. Obfervation. | : | DQagi 
There are a multitude of other Phezomena,that are produe’d from this 
fame Principle.jwhich as it has not been taken notice of by any yet that! 
know, fol think, upon more diligent obfervation, will it not be found the 
leaft confiderable. But Ihave here onely time to hint Hypothefes, and not 
to profecute them fo fully as I could with; many of them having a valt 
extent inthe production of a multitude of Phenomena, which have been 
by others,cither not attempted to be explain’d, or elfe attributed tofome — 
other canfe than what] haveaflign’d, and perhaps than the right; and 
therefore I fhall leave this to the profecution of fuch.as have more _— : 
one 
