224 PROPERTIES OF AIR 



to preserve, and to restore, the symmetry and 

 gradation of the whole. It would seem to be 

 with a view to this end, that we behold the 

 various species of dead and of common matter, 

 of which the universe is constituted, obeying 

 certain rules of rest, or of motion, according 

 to the class to which it especially belongs, 

 and of returning to their particular elements 

 after they have been separated from it. Whe- 

 ther it be solid, liquid, or gaseous mat- 

 ter ; whether it subsist by itself, or be integra- 

 ted and incorporated into other masses, it 

 obeys that universal law of nature, of obtain- 

 ing and preserving its proper level. It is in 

 obedience to these laws that solids, when they 

 are placed in media rarer than themselves, 

 gravitate and fall ; that water, elevated in 

 the air, above the surface of the ocean, flows 

 back into it; that fire, and gaseous bodies, 

 which are permanently elastic and expansible, 

 float on the surface of both. However this 

 tendency of preserving its proper level, may 

 be suspended, by the operation of external 

 causes, it, nevertheless, continues immutably 

 the same, and constitutes the vis insita, or 

 natural tendency which pervades every par- 

 ticle of the material world. I shall, there- 

 fore, proceed to detail the effects which are 

 produced, by different bodies, whenever this 

 state of order, and of subordination, is in- 

 verted and destroyed. 



