HAPTER X. 



jQN THE MECHANICAL PROPERTIES OF AIR IJf 

 JGENERAL, AND OF THE ATMOSPHERE 1^ , 

 PARTICULAR. 



SECTION I. 



On the Power of Gaseous Matter to expand 

 equally in every direction. 



As it was not my intention to extend the 

 observations I had to make, in describing the 

 different means by which gases are obtained, 

 the particular sources from whence they origi- 

 nate, or the materials of which they are com- 

 posed ; much less to enter into a detail of the 

 qualities they severally possess, or the various 

 changes which they undergo by chemical union 

 and combination, I shall proceed to explain 

 the physical properties which in them are in- 

 herent and essential; and the mechanical ef- 

 effects on other bodies, which those properties 

 are capable of producing. 



