v.] NITRATE OF SODA. 45 



liquor into sulphuric acid, so as to secure a com- 

 bination, after which the sulphate of ammonia is 

 crystallized in the usual manner. The chief bulk is 

 employed by the manufacturers of artificial manures, 

 who fully understand its value, and use it in proper 

 combination with other fertilizers. Its value depends 

 upon the percentage of ammonia which it contains. 



86. Nitrate of soda is an exceedingly popular 

 manure of the same class. It is a nitrogenous manure; 

 but it does not contain ammonia like the two preced- 

 ing manures. Here the nitrogen is present as nitric 

 acid, and this is combined with soda. It is a very 

 powerful manure of a white crystalline appearance. 

 It is largely imported from Peru and Chili, where it 

 exists as a crust near the surface of the land. This is 

 therefore a second and very important manure which 

 we receive from Peru. Nitrate of soda is largely used 

 for manufacturing purposes, besides being employed 

 for making artificial manures. Farmers have the 

 advantage of being able to supply their requirements 

 by the use of other nitrogenous materials, when the 

 supply of nitrate of soda is scarce. For other manu- 

 facturing purposes, nitrate of soda is actually necessary. 

 The demand for these uses therefore takes the pre- 

 cedence by the supply being secured, even at an 

 advanced price. Its agricultural value is usually 

 determined by calculating the nitrogen it contains, as 

 equal in value to the same quantity of nitrogen in the 

 form of ammonia; that is to say, the nitrogen, whether 

 in the form of a nitrate or in the form of ammonia, is 

 usually taken as of the same market value. 



87. Another source of nitrogen for fertilizing pur- 

 poses is the employment of woollen 'waste, 

 shoddy, also dried flesh and blood, fish re- 

 fuse, rape dust, seaweed, &c. These all 

 contain a large percentage of nitrogen, which by 

 decomposition can be converted into ammonia. 

 They render convenient supplies of ammonia to the 



