158 AMERICAN MANURES. 



in these substances is given out during their de- 

 composition as actual ammonia, and the value 

 of this nitrogen may be calculated by the amount 

 of time required for their decomposition. That 

 nitrogen in this shape is not immediately availa- 

 ble as food for plants, and consequently is not so 

 valuable as a manure containing ready formed 

 ammonia, is a fact that requires no reasoning on 

 our part. The decomposition of nitrogenous 

 substances, and the formation of ammonia, is a 

 work of time, and time is money ; practical ex- 

 periments have satisfactorily proved this to be 

 the case. Therefore this- potential ammonia can- 

 not be near so valuable as the actual. 



The cost of nitrogen in green ox bones can be 

 readily ascertained; if 100 Ibs. of these bones 

 contain 26*35 per cent, of insoluble phosphoric 

 acid, and 4*00 per cent, of nitrogen, as this phos- 

 phoric acid and nitrogen are the only substances 

 that give bones a value as a manure, we can 

 easily calculate the cost of nitrogen in this form. 

 According to the percentage given, each ton of 

 these bones would contain and show the following 

 value : 



527 Ibs. Insoluble Phosphoric Acid, at 4J cents $23.71 



80 " Nitrogen, at 15 cents 12.00 



Total $35.71 



This is a fair price for ground bones, and hence 

 15 cents per Ib. should be a fair price for the ni- 



