the Bubbles to a left Bulk, and greater fpecifick Gra- 
vity than the Air, elpecially ftnce Cold can be com- 
municated through .luch thin Shells, and the Tena- 
city of common Water is very fmall when com- 
pared to that of foaped Water ( whofe Bubbles, 
notwithaandmgthatTeuacity) arefoon deftroyed by 
the Preflure of the outward Air, as the Air within 
them cools > . 
■ 3d, If we fltould grant all the reft of the 
Suppofition, yet this Difficulty will remain. If 
Clouds are made up of hollow Shells of Water filled 
with . Air, why do not thole Clouds always expand 
when the ambient Air is rarefied, and prefles lefs 
than It did before, and alfo fulTer a Condenfation, 
as the ambient Air is condenfed by the Accumula- 
tion of the luperiour Air ? 
If this Condenfation and Rarefadion Ihould hap- 
pen to the Clouds, they would always continue at 
the lame Height, contrary to Obfervation’; and we 
Ihou d never have any Rain. 
From all this it follows, that the Condenfation 
and Rarefaason of the Vafours, which make 
Llouel^ mujt depend upon another Trinciple than 
the Condenfation and Rarefadiion of the Air ' 
And that there is fuch a Trinciple, I Jhall endea- 
vour to Jhew, 
« 
Lemma 
/ 
