THE DETERMINATION OF NITROGEN BY 



THE AZOTOMETRIC TREATMENT OF 



THE SOLUTION RESULTING FROM 



THE KJELDAHL DIGESTION. 



In the Chemiker Zeitung, vol. 12, p. 217, Sclioenherr states that, 

 if the sokition resulting from the Kjeldahl digestion is diluted, 

 neutralized, and an aliquot portion treated with sodium hypobro- 

 niite in an azotometer, the results obtained are very accurate. In 

 order to test this apparentl}^ very convenient method, the follow- 

 ing experiments were performed. 



The solution of sodium hypobromite was prepared by dissolv- 

 ing 50 gms of sodium hydrate in 125 cc. of water and adding 12 

 cc. of bromine. 



A. In order to test the h3'pobromite solution and the azotometer, 

 a solution of ammonia containing 3.265 gms nitrogen in one liter 

 was prepared. 



Ten cc. of this ammonia solution when treated with 50 cc. of hy- 

 pobromite, gave 32.60, 32.52, 32.60, 32.70 mgms. of nitrogen, the 

 theoretical amount being 32.65. 



B. A sample of cotton seed meal [Sample No. 2 from the Nitro- 

 gen Committee of the Association of Official Agricultural Chem- 

 ists, 188S], on treatment by the ordinary Kjeldahl method, gave 

 as an average of several determinations, 7.54 percent, of nitrogen. 

 In attempting to determine the nitrogen by the azotometer, re- 

 sults much lower were obtained, viz., 5.92, 5.30, 5.92, 5.40. 



C. When repeating the experiment, by mistake the solution 

 was not neutralized before treatment with hypobromite. The re- 

 sults obtained were 7.55, 7.67. Repeated without neutralizing 



7-67. 7-55, 7-54. 7-6o. 



Repeating these determinations, the following results on a sam- 

 ple of wheat bran and a mixed fertilizer, were obtained : 



