264 



The Philippine Journal of Science 



content of coal, Fieldner and Taylor 8 found that low results were 

 always obtained when the digestion was stopped as soon as the 

 solution became colorless. 



We have used piperidine with potassium sulphate and different 

 amounts of mercuric oxide and with sodium sulphate and dif- 

 ferent amounts of mercuric oxide without quantitative yields, 

 even when the mixture was heated for a period of ten hours. 



Table III. — Nitrogen determination of pi-peridine 

 method. 



modified Kjeldahl 



No. of sample. 



Sodium 

 sulphate. 



Potas- 

 sium 

 sulphate. 



Mercuric 

 oxide. 



Time 



heated. 



Nitrogen. 

 Theory, j Found. 



Total ni- 

 trogen 

 liberated. 





Grams. 

 

 

 8 



Grams. 

 8 



8 

 



Grams. 

 0.3 



Hours. 



10 



Per cent. 

 16.47 

 16.47 



Per cent. 

 12.63 



Per cent. 

 76.69 





0. 7 10 

 0.3 8 























The above methods were unsuccessful in giving quantitative 

 yields. 



Finally the method known as the Gunning-Arnold method, 

 which is recommended by Leach, ° for the determination of the 

 nitrogen in black pepper, was employed. This method gives 

 good results with pyridine when the heating is continued for a 

 considerable period after the solution becomes clear. An attempt 

 was made to substitute sodium sulphate for the potassium sul- 

 phate in the Gunning-Arnold method, but the substitution was 

 unsuccessful. 



Table IV. — Nitrogen determination of pyridine by the Gunning -Arnold 

 method and by a modified Gunning-Arnold method. 



um sul- | 



Grams. Hours. 



Theory. 



Found. 



Per cent. 



Per cent. 



17.72 



12.7 ' 



17.72 



12.0 



17.72 



13.6 



17.72 



15.8| 



17.72 



17.2 



17.72 



17.6 ! 



17. 72 



16. 6 1 



17.72 



16.3 ■ 



Total 



nitrogen 



liberated. 



76.2 



96.5 

 99 3 

 03. 6 

 92.0 



•Fieldner, A. C, and Taylor, C. A., Journ. Ind. & Eng. Chem. (1915), 

 7, 106. 

 * Loc. ciL 



