COMMERCIAL FERTILIZER MATERIALS 449 



carried by ground water to their present location. The con- 

 centration of the salts is considered by these authors as due 

 to surface evaporation and consequent upward capillary 

 movement of the highly charged ground water. 



248. Ammonium sulfate ((NH4)2SOi +)• — This fertil- 

 izer is a by-product from coke ovens and from the distilla- 

 tion of coal in gas manufacture.^ About one-fifth of the 

 nitrogen of the coal is thus driven off as ammonia, which is 

 caught in special washing devices. The mother liquid is then 

 distilled, the NHg being driven into sulfuric acid. The prod- 

 uct is later concentrated and the salt crystallized out. An- 

 other and simpler process provides for a direct union of the 

 gas and the acid, thus eliminating the washers. 



This fertilizer usually carries about 25 per cent, of am- 

 monia. It usually has a greyish or greenish color due to 

 coal-tar products. This commercial ammonium sulfate is 

 very soluble in water and has a characteristic taste. When 

 heated, it readily breaks up, giving off ammonia gas. It 

 is very acid to litmus paper, due to the union of a weak 

 base with a strong acid radical. The ammonia is very strongly 

 absorbed by the soil and also is used to a greater extent by 

 the plant than are the sulfate ions. It thus leaves in the 

 soil an acid residue^ which should be alleviated by lime if 

 the soil is not already supplied with plenty of active calcium 

 and magnesium. In a warm soil the ammonia is quickly 

 nitrified to the nitrate form. This transformation is general- 



^By-Product Colce and Gas Plants; The Koppers Company, Pitts- 

 burgh. 



Sulfate of Ammonia. Its Source, Production and Use; The Barrett 

 Company, New York. 



* Hall, A. D., and G-imingham, C. T., The Interaction of Ammonium 

 Salts and the Constitution of the Soil; Jour. Cliem. Soe. (London), 

 Vol. 91, pt. 1, p. 677, 1907. 



White, J. W.j The Mesults of Long Contvnued Use of AmwA)nium 

 Sulfate Upon a JResidual Limestone Soil of the Sagerstown Series; Ann. 

 Eep. Pa. State Coll., 1912-1913, pp. 55-104. 



Euprecht, E. W., and Morse, P. W., The Effect of Sulfate of Ammonia 

 on So%l; Mass, Agr. Exp. Sta., Bui. 165, 1916. 



