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cal salts contained in the faecal juices are very 

 volatile, and readily vaporizable, either when 

 the liquors are spread upon the soil as manure, 

 or when kept in loosely closed reservoirs be- 

 fore being used. The sulphate of ammonia, 

 on the contrary, is fixed, and hence the ma- 

 nure is, without exaggeration, not only aug- 

 mented in value but rendered so that it can 

 be preserved indefinitely. 



Human excrements, urine and solid matters, 

 by reason of the variety of salts, and especi- 

 ally of the ammonia and other nitrogenous sub- 

 stances, as also the phosphates which they con- 

 tain, are an abundant source of manure, merit- 

 ing more attention than has yet been given. 

 In many countries they experience the bene- 

 fits of its use but partially, because of their 

 neglect to fix the volatile ammoniacal salts ; 

 in others they discard the use of urines alto- 

 gether, and let them flow to waste as so much 

 useless material ; whilst in some places again, 

 they neglect the urines and solid matters and 

 pay no attention to their collection. This in- 

 difference, especially in large cities, deserves 

 to be seriously censured. In Paris they use 

 about one-third of the urines for the manufac- 

 ture of sulphate of ammonia; the other two- 



