URINE. 149 



as it is formed, and prevent the presence of 

 this gas in the atmosphere. Such an arrange- 

 ment, besides being profitable, as one source 

 of accumulating ammonia, would al.^o act 

 beneficially on the horses so confined, as there 

 can be no doubt, but that breathing such an 

 atmosphere constantly for some hours together, 

 induces a highly excited temperament, which 

 leads to, or at all events very much increases, 

 any local inflammatory action, and renders 

 the cure of such a malady, both difiicuit and 

 uncertain. 



These remarks, however, do not go to the 

 length of suggesting the use of gy[)sum as a 

 cure for such a stable, it is only a niearis of ab- 

 sorbing the noxious principle and turning it to 

 account, but ventilation, to a considerable ex- 

 tent, is the only cure and the best. 



Of the relative value of human urine, when 

 compared with other animal matters, it is cal- 

 culated by Macaire, that 100 parts of human 

 urine are equal, in their fertilizing power, to 

 1300 parts of the fresh dung of the horse, or 

 600 of those of the cow. Nothing more there- 

 fore can be said in favour of this manure ; it 

 must now be left to those who have ihe means 

 of applying and testing its real value. 



In speaking of nitrogen we have fully ex- 

 plained how ammonia acts as the pabulum of 

 plants, but we will here again shortly re[)eat it. 



Ammonia is composed of nitrogen and hydro- 

 gen. Now, when the ammonia, in a state of 

 solution, is absorbed by the spongelets of the 

 roots, decomposition takes place, the nitrogen 

 is assimilated to form the gluten of tho seed, 

 14 



