[ ] 
of Fire, or fubtil Matter fo violently agitated, that 
thefe component Parts of the Glafs do hardly touch 
one another : They fwim, if 1 may be allowed the 
Expreflion, in a Flood of this Matter of Fire ; and 
for this Reafon it is, that melted Glafs affefts the 
Colours of Flame. 
When this Subftance is expofed to the Air, the 
Goolnefsof this Fluid, which touches the Surface of 
the Glafs, cools that Surface firft j that is, brings the Par- 
ticles nearer together, braces tncirjl Pores, and thus im- 
prifons the Particles of Fire, which ftill fill the Infide 
of this Subftance. While thefe fiery Particles find 
Pores enough on the Surface, to move freely, the 
Glafs continues whole j but when the Giafs grows 
colder, that is, when the Pores of its Surface begin 
to confine thefe fiery Particles ; then their whole 
A&ion is exerted againft the Parts of the Glafs, 
which they break into a thoufand Pieces. In order 
to avoid this Fracas, nothing more is requifite than 
to keep the Pores on the Surface of- the Glafs wide 
enough, that the fiery Particles contain’d therein 
may pafs through, and fly off infenfibly. Now, this 
is what is done, by putting the hot Piece of Glafs 
into an Oven, the moderate Heat of which keeps 
thefe Pores open to a certain Pitch, and yet allows 
the Glafs to acquire its due Confidence in this State 
of middling Porofity : Wherein confifts the An- 
nealing of G'afs and other fufed Subftances. 
Hence it appears, that all unnealed Glafs carries 
within itfeif its Principle of Deftru&ion, which is 
the Matter of Fire imprifoned. But the Lachryma 
Bata-vica , or Glafs-Drop is in this refpeift, in a 
worfe Cafe ftill than unnealed Glafs : For befides 
that it has not been expofed to this fecondary Heat, 
which 
