Atmosphere. 93 



to the clouds, thus leaves room for the 

 exhalation of fresh quantities ; so that as 

 the vapour is considerably lighter than 

 the common atmosphere, and in conse- 

 quence ascends with great velocity, the 

 air during all this time is said to be dry, 

 notwithstanding the vast quantity of aque- 

 ous fluid that passes through it. 



In the physical economy also, another 

 provision is made for the continual reno- 

 vation of the atmosphere. Plants derive 

 subsistence from the very air that is unfit 

 for animal life, and in return, actually emit 

 that vital or dephlogisticated air, upon the 

 enjoyment of which the latter depends. 

 Thus we see a constant circulation of 

 benefits maintained between the two 

 great provinces of organized nature. The 

 plant purifies what the animal has poison- 

 ed ; in return, the contaminated air is 

 more than ordinarily nutritious to the 

 plant. Agitation with water appears to 

 be another of these restoratives. The 

 foulesi air shaken in a bottle with water 

 for a sufficient length of time, recovers a 

 great degree of its purity. Here, then 

 again, allowing for the scale upon which 

 nature works, we see the salutary effects 

 H2 



