xii, a, 3 Brill and Alinc'astre: Philippine Vegetables 129 



In a subsequent communication Drummond and Funk 1U report 

 that all the nitrogen of vitamine is not obtained by means of 

 the Kjeldahl method ; so the results recorded above for milk are 

 probably low. Compounds containing the pyridine ring possess 

 this same property of resisting digestion with sulphuric acid for 

 the determination of nitrogen. 17 Approximately three fourths 

 of the nitrogen of such bodies were obtained by this method. 



A method based upon this property of pyridine derivatives has 

 been employed by the authors for the determination of the pos- 

 sible vitamine content of some vegetables grown in the Philippine 

 Islands. 



DETERMINATION OF THE VITAMINE CONTENT OF VEGETABLES 



A portion of the fresh vegetable was dried at a low temperature 

 and very finely ground, and 100 grams of the ground foodstuff 

 was exhaustively extracted with methyl alcohol. The alcohol 

 was evaporated at low temperature, and the residue was taken 

 up in water and filtered. The filtrate was acidified with suf- 

 ficient sulphuric acid to make a concentration of 5 per cent. 

 Phosphotungstic acid was added to this solution to precipitate 

 the antineuritic substance. After standing for from four to 

 eight hours, the precipitate was filtered off, washed with 5 per 

 cent sulphuric acid and finally with alcohol, and dried in a 

 desiccator over sulphuric acid. The nitrogen was determined 

 in this residue by both the Kjeldahl and Dumas methods. 



Weighings of the precipitates and nitrogen determinations 

 were made to serve as checks. These determinations are in- 

 cluded in Table I. The calculations were made on the vege- 

 tables 18 as they were prepared for the table. 



The values for the vitamine content of Philippine vegetables 

 found by this method are usually higher than the results found 

 by Funk 19 for milk. However, they are presented here because 

 they have comparative value and for the purpose of stimulating 

 further investigation in quantitative determination of these 

 constituents. 



"Drummond, J. C, and Funk, C, Biochem. Journ. (1914), 8, 598. 



"Brill, H. C, and Agcaoili, F., This Journal, Sec. A (1917), 12, Kjeldahl 

 process. 



18 For description of Philippine vegetables, see Agcaoili, Francisco, ibid., 

 Sec. A (1916), 11, 91. 



"Funk, C, loc. cit. 



