128 The Philippine Journal of Science iw 



confirmation of the probability of the existence of a number of 

 antineuritic substances in rice polishings, yeast, wheat, and 

 bran, which are antineuritic in character, is the recent discovery 

 by Williams 10 of the peculiar action toward polyneuritic pigeons 

 of the hydroxypyridines, when they undergo dynamic isomerism, 

 and of the similar action of the vitamines isolated from autolyzed 

 yeast. 11 



If the vitamine content of foods does consist of a number of 

 distinct chemical compounds, the difficulty of quantitatively de- 

 termining it is readily seen. However, some attempts have been 

 made to make such an estimate. Phosphotungstic acid in alka- 

 line solution gives a blue color reaction with the antineuritic 

 substances. 12 Phosphomolybdic acid gives a similar color reac- 

 tion. 13 The intensity of the color is dependent on the concentra- 

 tion of the vitamine. The handicaps attached to these methods 

 are that no standard exists that can be used for comparison and 

 that other compounds give similar color reactions. 



The quantitative isolation is unsuccessful because of the pres- 

 ence of nitrogen compounds, which either accompany the vita- 

 mine or are the result of its decomposition. Vedder and 

 Williams 14 report that three successive extractions of rice polish- 

 ing with alcohol did not extract all the antineuritic properties of 

 the polishings. 



Funk 15 has made an attempt to determine the vitamine con- 

 tent of milk in the following manner: The milk was distilled in 

 a partial vacuum at 30° C. It was then powdered and dried to 

 constant weight. The powder was shaken with alcohol for two 

 hours and filtered, and the filtrate was evaporated to dryness. 

 The residue was extracted with water, acidified with sulphuric 

 acid, and treated with phosphotungstic acid. The nitrogen of 

 the phosphotungstic acid precipitate was determined by the 

 Kjeldahl method. By this method Funk estimates the vitamine 

 content of milk to range from 1 to 3 centigrams per liter or 

 from 0.001 to 0.003 per cent. 



"Williams, loc. cit. 



11 Williams and Seidell, loc. cit. 



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

 O., and Macallum, A. B., Journ. Biol. Chem. (1912), 11, 265; (1912), 13, 

 363. 



13 Folin, O., and Denis, W., ibid. (1912), 12, 239. Funk, C, and Macallum, 

 A. B., Biochem. Journ. (1913), 7, 365. 



M Vedder, E. B., and Williams, R. R., This Journal, Sec. B (1913), 8, 175. 

 "Funk, C, Biochem Journ. (1913), 7, 211. 



