PRACTICE XV 



NITRIFICATION 



Bring 40 cc. of the standard ammonium sulfate solution into a 

 500-cc. measuring flask, add 0.3 g. of dipotassium phosphate, 0.5 g. 

 of calcium carbonate, and about 2 g. of fresh, rich garden soil, and 

 make up to the mark. Mix well and let settle. 



Place 600 g. of clean, washed, and dried white sand in a perco- 

 lator. Upon this pour 100 cc. of the above solution in such a way 

 as to wet the whole surface of the sand. Allow to stand one hour, 

 wash with about 500 cc. of ammonia-free water, collect the wash- 

 ings, and make up to exactly 500 cc. Place 250-cc. portions in 

 Kjeldahl flasks and determine nitrogen in the usual way. Com- 

 pare the amount of nitrogen found with that originally applied in 

 the ammonium sulfate. 



Titrations (1) ................................................................................... cc. NH 3 



(2)- ......................... cc.NH 3 



Av ............................................................................................. cc. NH 3 



N found .................................................................................. mg. 



Add another 100-cc. portion of ammonium sulfate solution to 

 600 g. of clean, washed, and dried sand held in a percolator, cover, 

 and allow to stand in a dark place at warm room temperature for 

 six weeks, adding water from time to time to prevent complete 

 drying. Then wash out and determine the ammonia nitrogen as 

 directed above. 



Titrations (1) ................................................................................... cc. 



(2).- ......................................................... CC.NH, 



Av ............................................................................................. cc. NH 3 



N found .................................................................................. mg. 



Per cent N nitrified ........................................................... 



What change has been brought about, and how ? Why does not 

 all of the nitrogen added appear in the second distillation ? Why 

 was the percolator kept in the dark ? Why was K 2 HP0 4 added ? 

 CaC0 3 ? garden soil? Why was the ammonium sulfate solution 

 poured upon sand instead of being left in a flask ? 



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