170 MANURE. 



242. Urea is composed, according to Dr. Prout, 

 of carbon 19*99, oxygen 26*66, hydrogen 666, ni- 

 trogen 46*66. These elements are so beautifully bal- 

 anced, that they afford only carbonic acid and am 

 monia ; though the chemistry of every reader, may 

 not understand how these elements produce cyanic 

 acid and ammonia. The salt cyanate of ammonia, 

 has actually been formed by modern chemistry, which 

 has thus succeeded in forming a true organic product, 

 or product of living action, or rather of chemical 

 action guided by living principle. In all animal 

 evacuations containing urea, that may be consid- 

 ered, as so much carbonate of ammonia of the 

 shops. 



243. The peculiar animal acid which has been 

 mentioned as forming so essential a part in these 

 liquid excretions, is called uric acid. It is not, like 

 urea, changed by exposure, into ammonia. It con- 

 tains a large portion of nitrogen, which, under the 

 influence of growing plants, is let loose, and may 

 then form ammonia. Its composition is as follows : 

 carbon 36*11, hydrogen 2-34, oxygen 28-19, nitrogen 

 33-36. 



The peculiar principles of the liquid evacuations 

 having been explained, their constitution may be 

 now stated. They are, it will be remembered, at 



