101-103] Nitrogen in Nitrates 69 



N.B. — This is the ordinary method used to determine the 

 amount of ammonia in ammoniacal salts. 



Operation II — Determine the nitrogen by means of the 

 acid process (paragraphs 92-95). The sulphuric acid used, in 

 this case, will drive off all the 'nitric' nitrogen in the form 

 of HN0 3 . Thus the percentage of ammoniacal + organic 

 nitrogen will be obtained. 



Operation III. — Determine the total nitrogen as explained 

 in paragraphs 97-99. 



101. Calculation. — By these three operations we obtain 

 three results. The first gives the percentage of ammoniacal 

 nitrogen. The difference between the second and the first is 

 the percentage of organic nitrogen, and the difference between 

 the third and the second is the percentage of ' nitric ' nitrogen. 



RAPID METHODS FOR THE DETERMINATION 

 OF NITROGEN IN NITRATES 



102. In cases where nothing but the percentage of 'nitric' 

 nitrogen is required, as in alkaline nitrates, the above method 

 would be very long and tedious. Therefore, three methods 

 are here given, each of which has its special recommendations. 



103. Ulsch's Method.— This method is the most gener- 

 ally applicable, and is of especial value in the analysis of 

 alkaline nitrates, and mixed manures which contain nitrates 

 but not ammonium salts. 



Method employed. — The nitrate is reduced by iron and 

 dilute sulphuric acid. Ammonium sulphate is thus formed. 

 The ammonia is driven off and estimated as before. 



Substance used. — Potassium nitrate, KN0 3 . Weigh out 

 accurately about 2 grams of pure potassium nitrate, and dissolve 

 in a little water. Introduce the solution into a 100-c.c. flask, 

 with all the precautions used in making up a standard solution. 



