PRACTICE XXIV 



DETERMINATION OF NITROGEN IN FERTILIZERS 



Weigh out 0.5 g. of each of the following materials and use 20 cc. 

 of standard hydrochloric acid in the receiver. 



1. Ammonium sulfate. 



2. Dried blood. 



3. Sodium nitrate. (Use the Kjeldahl method modified for nitrates. 

 ^Yith the finely ground nitrate in the Kjeldahl flask mix thoroughly 2g. 

 of salicylic acid. Add slowly, cooling if heat is evolved, 30 cc. of con- 

 centrated sulfuric acid and, gradually, about 2 g. of zinc dust ; shake 

 thoroughly, and let stand over night. Then add mercury and digest as 

 usual. In the distillation use 1.5 times the usual amount of alkali.) 



How would the reaction of the soil be affected by the residues 

 left by each of these materials when used to supply nitrogen for 

 plant growth ? 



52 



