5d ON NITROGEN. 



nutrition to plants ; and thus the medium in 

 which both exist, namely, the atmosphere, is 

 maintained constantly unchanged. 



" The presence of a rich and luxuriant ve- 

 getation may be conceived without the pre- 

 sence of animal life. But the existence of 

 animal life, constituted as we now are, is un- 

 doubtedly dependant on vegetable life for its 

 support;'^ but both are interwoven in such a 

 manner as to call forth our highest expression 

 of admiration of the system, and devotional 

 feelings of gratitude to the Being who has so 

 constituted this scheme, and who has given to 

 man the power in some measure to compre- 

 hend its perfections. 



ON NITROGEN. 



Nitrogen, the next in order and in necessity 

 for the development of plants, is only known 

 in its gaseous state, or in combination with 

 other gases in a fluid or solid state, as in ni- 

 tric acid and salammoniac, or combined with 

 salts in a solid form, such as nitrate of potash, 

 &c. 



Nitrogen also forms the great bulk of the 

 atmosphere surrounding the earth, 100 parts 

 containing 79 parts nitrogen, and 21 oxygen; 

 and it is remarkable, that although these 

 gases possess very different specific gravities, 

 that the atmosphere under all circumstances 

 is composed of exactly these proportions, 



