SOURCES OF AMMONIA. 155 



those manufactured from organic substances, the 

 amount of actual ammonia is very small. It 

 requires no reasoning to prove that actual am- 

 monia is far more valuable than nitrogen in the 

 form of so-called potential ammonia, as the first 

 named as found in Peruvian Guano, fermented 

 dung, and urine has a marked effect upon the 

 growth of plants, while other substances that are 

 not quickly and readily decomposed, such as 

 wool, horns, hoofs, etc., may contain an equal 

 amount of nitrogen, and yet have no apparent 

 effect upon the growth of vegetation. 



Manufacturers in giving analyses of their 

 manures make no distinction between nitrogen 

 as actual ammonia, and nitrogen in organic 

 matter ; but both are given as actual ammonia. 

 But as we have determined the amount of each ' 

 in the manures analyzed (Chap. VII.), we shall 

 give them a value as nearly in accordance with 

 the condition in which they are found as possi- 

 ble. We shall be guided by the same rule in 

 the valuation of this article, as we were with 

 phosphoric acid, viz :- the cost of production and 

 preparation, and its value in the different mater- 

 ials from which the manufacturers obtain it. 

 Nitrogen is usually procured from the following 

 sources of supply : Peruvian Guano, bones, 

 hoofs, horns, blood, and other organic remains, 



also from the crude sulphate of ammonia. All 

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