‘ 
MricrocRaPHta ) 
fiderable one,whilft they are ina ftate of Futon. For Fluidity,asl eHewhere 
mention, being nothing but an effet of avery firore and quick {baking avotion, 
whereby the parts arc,asit were,loofened from each other,and confequently leave 
an interjaceut fpace or vacnitys it follows, that all thofe fhaken Particles mut 
neceflarily take up much more room then when they were at reft, and lay 
quietly upon each other, » And this is further confirmed by a Potof hoyling 
Alabafter; which will wees: rife a'fixth or eighth part higher im the Por, 
whilft itis boyling, then it wil] remain at, both before and after it be boyly 
ed.The reafon of whichodd Phenomenon ( tohintithere only by the way) 
is this, that'there is in the curious powder of Alabafter, and other calcining 
Stones, a certain watery, fubftance, whichis fofixt and included. with the 
folid Particles, that tillthe heat be very confidetable they will not fly aways 
but after the heat is increafed to fuch adegree.,' they break ont every way 
in vapours, and thereby fo fhake and loofen the {mal} corpulles. ofthe Pow- 
4i 
der from each other, that they become perfettly of thenature.of.afluid bo, © 
dy, and one may move aftick to and fro through it; and {tiv,it as ealily as 
water, and the vapours burft and break out in bubbles juftas in povling 
water,and-the like; whereas, both. betore Cots te patts.are flying 
away, andafter they are quite gone 4. that is, before and after it have done 
boyling,all thofe effectsiceafe , and a ftick is.as diffieultly moved to and fro © 
in it asinfand, or the like. Which Explication I could ealily prove, had I 
time; but this is not a fit place forit.):: a4 + 
To proceed therefore; I fay,that the droppi of this expanded Body ine : 
to cold Water, does make the parts of the Glafs fuffer a double contraction: ‘ 
The firft is, of thofe parts which are neer the Surface of the Drop, For Cold, 
asI {aid before,contracting Bodies, that is,by the abatement of the agitating fa- 
culty the parts falling neerer together; the parts next adjoying to the Water 
mutt needs lofe much of their motion , and impart it to the Ambient-water 
(which the Ebullition and commotion of it manifefts) and thereby become 
a folid and hatd croft, whilft the innermoft parts remain yet fluid and ex+ 
panded ; whence,as they grow cold alfo by degrees,their parts mutt neceffa- 
_rily be left at liberty to be condenfed., but becauleof the hardnefs of the 
outward cruft,the contraction cannot be admitted that way;but there being 
many very imall, and before inconfpicuous, bubbles in the fubftance of the 
Glafs,upon the fubfiding of the parts of the Glafs,the agil fubftance contain- 
ed inthem has liberty of expanding it felfa little,and para ite bubbles 
grow much bigger;whichis the fecond Contrattion.s And both thefe arecon- 
firmed fromthe appearance of the Drop it felf: for as for the outward parts, 
we fee, firft,that it is irregular and fhrunk,asit were; which is cawled by the 
yielding a little of the hardened Skinto a Contrattion, after the very out- 
moft Surface is fettled 5 and asfor the internal parts, one may with ones 
ed Eye perceive abundance of very confpicuons bubbles, and withthe 
ae 
_Microfcope many more. 7 eq ti eee toc 
The Confideration of which Partitalars will eafily make the Third Pofiti; 
on probable,that is,that the of the drop will be of a very hard, though 
of a rarified Texture ; for ifthe outward parts of the Dab. by reafon.of its 
hard eruft, will indure very liteleContraction, and theagil Particles, inch 
oO il- 
H ded 
