CHAPTER XXV 

 AMMONIA 



THE interest in ammonia centers largely in the use of liquefied 

 ammonia for refrigeration, in the employment of the gas in making 

 carbonate of soda, and in the value of its compounds as fertilizers 

 and explosives. 



Manufacture. Ammonia is formed when nitrogenous or- 

 ganic matter is heated, in absence of air. It was formerly made 

 By distilling scraps of hoofs, horns, and hides. The solution of the 

 gas thus obtained was called " spirit of hartshorn." The pungent 

 odor of smoldering feathers, leather, or fur is, therefore, partly due 

 to its presence in the escaping vapors. From the proteins of the 

 original plants, coal derives a considerable proportion of nitroge- 

 nous matter. Hence, when coal is distilled for the making of 

 coal gas, or, on a far larger scale, for the making of coke, much 

 ammonia can be separated, by washing with water, from the mix- 

 ture of gases produced. The aqueous solution is separated from 

 the tar, neutralized with sulphuric acid, and evaporated to give 

 the salt, ammonium sulphate (NH 4 )2SO 4 . 



NH 3 + H 2 O-+NH 4 OH (ammonium hydroxide). 

 2NH 4 OH + H 2 S0 4 - (NH 4 ) 2 SO 4 + 2H 2 0. 



The distillation of coal is the chief source of commercial am- 

 monia. In the United States, prior to the war, nearly all the 

 coke was made in " beehive " ovens, in which the vapors issuing 

 from the coal are burned, uselessly, on the spot. Since the war, 

 about 75 per cent of coke is made in " by-product " coke ovens, 

 in which the ammonia and innumerable other by-products are 

 collected and utilized (see p. 424). In Scotland, oil-bearing shale 



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