3 8 SCIENTIFIC AGRICULTURE. 



from this small but essential constituent of the at- 

 mosphere." 



78. Ammonia exists in the air in even more mi- 

 nute quantities than carbon dioxide, so minute that 

 only the most delicate tests can indicate its pres- 

 ence, and the most sensitive balance would not be 

 affected by the quantity in a room of ordinary size, 

 and yet it is of essential value to all kinds of vege- 

 tation. 



79. A close study of the nature and composition 

 of the atmosphere shows that it is admirably adapted, 

 by its physical and chemical properties, to the wants 

 of animals and plants. " It conveys to them their 

 nourishment and life ; it tempers the heat of summer 

 with its breezes; it binds down all fluids, and pre- 

 vents their passing into a state of vapor ; it supports 

 the clouds, distills the dew, and waters the earth with 

 showers ; it multiplies the light of the sun, and diffuses 

 it over earth and sky ; it feeds our fires, turns our 

 machines, wafts our ships, and conveys to the ear all 

 the sentiments of language and all the melodies of 

 music." 



80. Science teaches us that Infinite Wisdom has 

 shown, in these invisible atmospheric agencies at 

 work around us, the same skill and benevolence, 

 the same goodness and power, as in the more mani- 

 fest displays of divine energy. Silently but surely 

 they accomplish their appointed work of contribut- 

 ing directly to the nutrition of organic bodies, and 

 by their action upon solid substances continually 



