72 MANUAL FOR SUGAR GROWERS. 



economical, the former, wlien pure, contaiuing 16.4 

 and the latter 21.3 per cent, of nitrogen ; hence the 

 expenses in handling are reduced to a small amount, 

 the point to be considered in colonial agriculture. 



Nitrate of soda is found as a dej)osit in certain 

 parts of South America where the rainfall is ex- 

 tremely limited ; it is found mixed with clay, gypsum, 

 and other impurities, and is purified by dissolving 

 out the nitrate with water and recovering the nitrate 

 by evaporation. Good commercial nitrate of soda 

 as employed for manures usually contains from 

 ninety-five to ninety-eight per cent, of real nitrate 

 of soda. This manure is, as will be seen from what 

 has already been said upon the subject of nitrifica- 

 tion, a quick-acting one. It must be remembered 

 that the soil has no retentive power for nitrates, 

 hence in Avet seasons or on wet lands there is great 

 liability to loss from drainage. 



Sulphate of ammonia is obtained from the am- 

 moniacal liquor produced in the manufacture of coal- 

 gas ; it usually occurs in commerce in a very pure 

 state, containing from ninety to ninety-eight per 

 cent, of real sulphate of ammonia. It is sold on the 

 basis of the ammonia it contains ; thus twenty-four 

 per cent, of ammonia is equal to ninety-three per 

 cent, of sulphate of ammonia, while twenty-five 

 per cent, of ammonia is equal to about ninety-seven 

 per cent, of sulphate of ammonia. Like all chemical 

 manures it should be purchased on the basis of 

 analysis. Sulphate of ammonia is the most satis- 

 factory nitrogenous manure the sugar grower can 

 import ; it should be employed as a top-dressing in 



