254 



SOILS AND MANURES 



the liquor is saturated with 

 lime and distilled ; the 

 volatile ammonia gas passes 

 over, is neutralised with sul- 

 phuric acid, and the salt thus 

 formed is crystallised from 

 saturated solutions. A typical 

 form of plant used in gas- 

 works for this purpose is 

 shown in the illustration l 

 (Fig. 31). The product ob- 

 tained in this way is practi- 

 cally free from all impurities 

 except those contained in the 

 sulphuric acid or picked up 

 incidentally. It always con- 

 tains a certain amount of 

 moisture, but in well-made 

 samples the total solid im- 

 purity should not exceed 2 or 

 3 per cent. 



The production of sulphate 

 of ammonia in other indus- 

 tries is carried on in a very 

 similar manner. About 65 

 per cent, of the total output 

 comes from gasworks, 20 per 

 cent, from shale-works, 10 per 

 cent, from iron-works, and the 

 remaining 5 per cent, from 

 various carbonising works. 

 More than 300,000 tons is 



1 Copy supplied by Messrs. R. 

 and J. Dempster, Ltd., Manchester. 



