CHAPTER X. 



Making Fertilizer Mixtures with Cyanamid. 



MIXTURES WITH AMMONIUM SALTS. 



Cyanamid contains about 55 per cent. CaO, of which about 

 30 per cent, is present as CaCNg, 21 per cent, as Ca(OH)2, 

 and 4 per cent, as CaCOg and other forms. Most of the 

 calcium, therefore, dissociates readily and can react when 

 brought into contact with certain bodies. In the presence of 

 ammonium sulphate for instance, a double decomposition takes 

 place as follows: 



Ca(OH), + (NH,),SO, — CaSO, + 2NH3 + 2H,0. 



Hence, if Cyanamid and ammonium sulphate are mixed 

 alone there will be a large loss of ammonia. The same kind 

 of reaction takes place with other ammonium salts. 



If, however, as is practically always the case, there is 

 present an adequate amount of acid phosphate or other acid 

 material, the acid of the acid phosphate immediately fixes the 

 free ammonia and prevents its escape. The ammonia is com- 

 bined probably as ammonium phosphate or as calcium ammo- 

 nium phosphates, or both. To prevent loss of ammonia, there- 

 fore, it is only necessary to have a sufficient amount of acid 

 material present so that the resulting mixture will be acid in 

 reaction. This condition is obtained when the amount of 

 Cyanamid does not exceed 100 pounds of powdered Cyanamid 

 or 200 pounds of granulated Cyanamid per 800 pounds of 

 ordinary acid phosphate containing 14 or 16 per cent, of 

 available phosphoric acid. Such mixtures have been tested 

 in practical fertilizer manufacturing and show no losses of 

 ammonia. The quantity of ammonium sulphate present is 

 practically immaterial. Acid fish contains some nitrogen as 

 ammonium sulphate, and should be mixed in accordance with 

 the above rule. 



