58 



APPENDIX. 



The statements in the different text-books as to the quantity 

 of manure produced by the horse are such as naturally to 

 perplex the student. This discrepancy is due, however, 

 to the different methods adopted by different writers of 

 calculating this amount. The subject is further discussed 

 in the footnote to p. 29. The following analyses of horse- 

 manure may be valuable for reference. They are taken 

 from Storer's ' Agricultural Chemistry/ vol. i. p. 496 : 



NOTE X. (p. 24). 



THE NATURE OP THE CHEMICAL KEACTIONS OF AMMONIA 

 " FIXERS." 



For the student, the exact nature of the chemical re- 

 actions taking place may be of interest. 



In the first place, it must be distinctly understood that 

 the form in which ammonia escapes from the manure- 

 heap is not, as is so commonly erroneously stated in 

 agricultural text-books, as " free " ammonia. Whenever 

 ammonia is brought into contact with carbonic acid, car- 

 bonate of ammonia is formed. When it is remembered 

 that carbonic acid is by far the most abundant of the 

 gaseous products of the decomposition of organic matter, 

 it will be at once seen that free ammonia could not exist 

 .under such circumstances. 



