[ I 77 ] 
der the Hammer ; and does not burfl: upon break- 
ing the fmali End. 
Exper. 7. The Drops that are made by letting 
them cool in the Air, produce no other Effects 
than thofe which have been annealed. 
The firft natural Philofophers who endeavoured to 
inveftigate the Caufe of thefe Phenomena, imagined 
that they found it in the Air. Some of them fup- 
pofed, that this Air was fhut up in the Drop by the 
Cruft which the cold Water forms on its Surface 
while it is yet red-hot; and attributed its Rupture 
to the Violence with which this Air iflued thro’ the 
too narrow Pafl'age made for it, in breaking the 
fmali End of the Drop. Others maintained on the 
contrary, that the Drop, in this State, contained no 
Air at all, nor any thing but Particles of Fire, or 
fubtile Matter; or, in one Word, a Vacuum of Air ; 
and that the fudden burfting of the Drop was oc- 
calioned by the impetuous Entry of the Air into 
this fort of Vacuum. In fine, the Cartejians have 
fubftitutcd their fubtile Matter in the room of this 
exterior Air, and fay, that the Drop is burftcd by 
the lcfs fubtile Particles of this Matter; which enter- 
ing with Force into the Drop by the Opening made 
therein, and finding large Pores on the Infide, and 
fmali ones on the Outfide, burfl: the Sides of the 
Drop, by rufhing from the Centre to the Circum- 
ference, wherewith its Paffage is obflru&ed. 
Melf. Mariotte and Homherg came afterwards ; 
Being provided with an Air Pump, they caufcd one 
of thefe Drops to be broken in Vacuo ; and Hom- 
Z . berg 
