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 ((NH 4 ) 2 S0 4 + ).— This fertil- 

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

 tion of coal in gas manufacture. 1 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 NH 3 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 2 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- 



1 By-Product CoTce and Gas Plants; The Koppers Company, Pitts- 

 burgh. 



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

 Company, New York. 



2 Hall, A. D., and Gimingham, C. T., The Interaction of Ammonium 

 Salts and the Constitution of the Soil; Jour. Chem. Soc. (London), 

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



White, J. W., The Besults of Long Continued Use of Ammonium 

 Sulfate Upon a Besidual Limestone Soil of the Hagerstown Series; Ann. 

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



Ruprecht, R. W. r and Morse, F. W., The Effect of Sulfate of Ammonia 

 on Soil; Mass. Agr. Exp. Sta., Bui. 165, 1915. 



