CHAPTER X 

 NITROGENOUS MANURES 



THE most widely distributed nitrogenous ma- 

 nures are nitrate of soda and sulphate of ammonia. 

 A third class of purely nitrogenous manures is 

 that represented by animal waste. These latter 

 products are of considerable agricultural impor- 

 tance, although the manure trade does not seem 

 to take them sufficiently into account. These 

 three forms of nitrogenized manures are not 

 only differentiated by their chemical compo- 

 sition, but by their mode of action in the soil. 

 They form, therefore, three distinct classes, which 

 will be examined. 



Nitric acid compounds have been known 

 for a long period. It is probable, according to 

 Herpath, that the ancient Egyptians used nitrate 

 of silver to make their inscriptions on the bands 

 in which they wrapped their dead; it is the same 

 chemical compound as that known as infernal 

 stone, which is used to mark linen and the skin. 

 As far back as the eighth century of the Christian 

 era, Geber and Marcus described a body which 

 they called salpetrae, which corresponds with 

 saltpetre, or nitrate of soda. In the twelfth 



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