$2 
MicroGRAPHIA. | 
It may therefore, perhaps; be worthy fome Phyficians enquiry, whether _ 
chen’hdiahihot i Seieaiiis mixt with the Urine in which the Gravel 
~ orStone lies; which may again make it diflolve it, the firft of which feems 
by it’s regular Figures to have been fometimes Cry/talliz'd out of it. For 
whether this Cryftal/ization be made in the manner as Alxm, Peter,&c. are. 
as yg ofa cooling liquor, in which, by boyling they have been 
diffolv'ds or whether it be made inthe manner of Tartatum Vitriolatum, 
that is, by the Coalitiox of an acid and a Sulphureous tub{tance, it feems 
not impoflible,but that the liquor it lies in,smay be again made a diffoluent 
of it. But leaving thefe inquiries to Phyficians or Chymifts, to whom 
it doesmore properly belong, I fhall proceed. = — 
Obfervs XIII. Of the fmall Diamants, or Sparks im Flints, . 
c \Hancing to break a Flint ftone in pieces, I found within ita certain a 
cavity all crufted.over with a very pretty candied fubftance, fome — 
“ie parts of which; upon changing the pofture of the Stone, inrefpedt 
athe ducident light, exhibited a number of {mall, but very vivid re- _ 
flections ; and having made ufe of my: Aficrofcope, I could perceive the | 
whole furface of that cavity to be all befet with a multitude of little 
Cryftaline or Adamantine bodies, fo curioufly thap’d, that it affordeda — 
not unpleafing object. 9 : a 
Haying confidered thofe vivid repercuffions of light, found them tobe — 
pwaigrse J: oe the plain external futtface of thefe regularly figured — 
bodies (which afforded the vivid refieétions) and partly to be made — 
from within the fomewhat pe/ucid body, that is,from fome furface of the — 
| a es oe to that fuperficies of it which was.next the eye. eee 
And becaufe thefe bodies were fo fmall, that 1 could not well cometo 
make Experiments and Examinations of them, I provided me feveral — 
{mall frie of Cryftals or Diamants, found in great quantities in Corm- — 
wall.and are therefore commonly called Corzi{h Diamants: thefe being — 
very pellucid, and growing ina hollow cavity of a Rock (asThavebeen 
feveral times informed by thofe that have obferv'd them) much afterthe — 
fame manner as thefe do in the Flint ; and having befides their outward 
furface very regularly fhap'd, retaining very near the fame Figures with — 
fome of thofe I obferv'd in the other, became a convenient helpto mefor. — 
the Examination of the proprieties of thofe kindsof bodies, 5° 
And firlt for the Reflections ; in thefe I found it very obfervable, That 
_ the brighteft reflections of light proceeded from within the pe/xcid bodys 
that is, that the Rays admitted a the pellucid fub{tance in theit — 
getting out on the oppofite fide, were by the contiguous and ftrongre- 
ecting {urface of the Air very vividly reflected, fothat more Rays were 
reflected to the eye by this furface, though the Ray in entring and getting 
out of the Cryftal had fuffer'd a double refraction, than there werefrom 
the ‘ia furface of the Glafs where the Ray had fuffer'd no — 4 
ata FE 
