224 THE CHEMISTRY OF CREATION. 



nected with, and even dependent upon, the 

 existence of a gaseous ingredient of the air, so 

 small in quantity as to have long escaped 

 the detection of the most accurate experi- 

 menters. 



Man, it is true, is an omnivorous creature. 

 His food consists of both kinds, animal and 

 vegetable. Il^ may be said, all the nitrogen he 

 requires he can obtain in the greatest abund- 

 ance from the flesh he consumes as food ; and 

 no doubt the greater part of those tissues of the 

 human body abounding in nitrogen, such as 

 muscle, &c., are nourished from this source. 

 But the difficulty is only put a step back by 

 this consideration ; for we must then inquire 

 from whence do these animals used as food, and 

 themselves feeding exclusively upon plants, ob- 

 tain their nitrogen? This discovery furnishes 

 us with a sufficient answer, it is from the 

 vegetable kingdom ; and plants derive it chiefly 

 from the ammonia of the atmosphere. It is 

 thus by an interesting and beautiful series of 

 links that this important process the supply of 

 nitrogen is carried on. Ammonia, a minute 

 component of the atmosphere, containing the 

 essential element for the animal kingdom, is 

 essential to vegetation ; a vegetable diet is essen- 

 tial to the animals we use for food ; and a mixed 

 diet is, without doubt, essential to the healthy 



