Lesson xvi.] ATMOSPHERE. 79 



The following is Mr. Dalton's table of the 

 weights of the different gases constituting the at- 

 mosphere : 



Incites of Mercury 



Azotic 6as 23.36 



Oxygenous Gas ' 6.18 



Aqueous Vapour -14 



Carbonic Acid Gas .02 



30.00 



Table of the proportional weights of the dif- 

 ferent gases in a given volume of atmospheric air, 

 taken at the surface of the earth : 



Azotic Gas 



Oxygenous Gas 

 Aqueous Vapour 

 Carbonic Acid Gas 



100.00 



The uses of the Atmosphere are so many and 

 great, that it is absolutely necessary, not only to the 

 comfort and convenience of mankind, but even to 

 the existence of all animal and vegetable life. Ex.- 

 periments which have been frequently made with 

 an instrument called an air pump, place it beyond 

 doubt that without the air or atmosphere, no. 

 animal could exist, or even be produced : with- 

 out its aid all vegetation would cease, neither 

 would there be any great degree of either inflam- 

 mation or combustion. Sound could not be pro- 

 duced without it, nor would there be either rains 

 or dews to moisten the ground : in short, all our 

 S 4 reflections 



