NITROGENOUS FERTILIZERS 169 



Exercise II. — Examination and identification of nitrogen 

 fertilizers. 



Materials. — Set of fertilizers (comprising sodium nitrate, am- 

 monium sulfate, cyanamid, dried blood and tankage), evaporating 

 dish, phenoldisulphonic acid, ammonia, funnel and filter paper, 

 litmus paper, hand lens, flame. 



Procedure. — It is well for the student to be able to identify 

 the common fertilizers and to know a few practical tests when the 

 identity is in doubt. The following outline is given with this end 

 in view. 



Sodium Nitrate 



This fertilizer appears in clouded light yellowish crystals, soluble 

 in water and rather deliquescent. It has no marked odor. 



Hold a crystal in the flame. Note the brilliant yellow color. 

 This is a test for the element sodium. 



Test for the nitrate part of the fertilizer by moistening a crystal 

 in an evaporating dish with a drop of phenoldisulphonic acid. 

 Allow to stand a few minutes and then dissolve in a little water. 

 Now neutralize with ammonia and obtain the yellow color charac- 

 teristic of nitrates. 



Ammonium Sulfate 



This fertilizer is a light grayish colored salt, finely ground and 

 soluble in water. Heat a little in an evaporating dish and note the 

 odor of ammonia. 



Cyanamid 



Cyanamid is a fine, dry, black powder which carries besides its 

 nitrogen compound, carbon and lime. The carbon may be tested 

 for by rubbing the fertilizer between the fingers. Dissolve as much 

 of the fertilizer as possible in water, filter and test the filtrate with 

 litmus paper. It should be intensely alkaline on account of the 

 lime it contains. The physical characters of the fertilizer are such 

 as to make it easily recognized. 



Dried Blood and Tankage 



These materials can be easily identified and distinguished by 

 their physical properties, especially if a hand lens is used. Consid- 

 erable hair and bone is likely to be found in tankage. The odor of 

 both is characteristic. Study each fertilizer until identification is 

 easy. 



