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which keeps its Pores open, till the Glafs has ac- 
quired its due Confidence, for Fear that the Cool- 
nefs of the Air alone fhould not clofe its Pores foon 
enough, and imprifon a fufficient Quantity of the 
igneous Matter, it is fuddcnly thrown into cold 
Water, which by its Coldnefs and Weight is fitter 
than the Air to produce fuch an Effed fpeedily and 
effectually. Wherefore the only furprifing Circum- 
ftance in thefe Glafs-Drops is, that any of them re- 
main without breaking, by the great Quantity of 
igneous Matter fuddenly (hut up in them by the 
cold Water. And indeed this Accident befalls more 
than one half of them ; and thofe that efcape, doubt- 
lefs owe their Prefervation to the fpherical or cy- 
lindrical Figure of the compad Shell, which the 
Coldnefs of the Water forms on their Surface : For 
it is well known that this Figure produces an Equa- 
lity of Refiftance on all Sides, which confiderably 
encreafes the refilling Force : And this is the firft 
Reafon why, as foon as this Equilibrium is broken, 
either by rubbing away one Side of this Surface, or 
by making a Hole in it, or, in fine, by breaking the 
fmall End of the Drop ; the Refinance is inftantly 
overcome, and the igneous Matter, imprifoned with- 
in the Glafs, and conftantly upon the Strain againft 
it, burfis it into Powder. 
This defiroyed Equilibrium is but one Difpofi- 
tion that favours the Effed of the imprifon’d igne- 
ous Matter : But the Communication which is opened 
for it with the fubtile exterior Fluids, roufes this 
Matter which is in a State of Inadivity, develops its 
Spring, kindles it fomewhat in the Manner of the 
Phofphorus, which produces no Effed while clofe 
(hut 
