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IT has been demonstrated1–5 that prolonged and vigorous saponification of the mixed free acids of fish-liver oils causes remarkable changes in their chemical structure and in the absorption in the ultra-violet. When saponifying the acids of cod liver oil in this way, I observed a remarkable change in the Carr and Price reaction of these acids.

HARRIS has showed that the reducing capacity of animal tissues titrated against 2.6 dichlorophenolindo-phenol (as indicated by Tillmans and Szent-Gyorgyi) in acid solution, coincides with the biological activity.

FOR the determination of vitamin A by means of the reaction of Carr and Price, the blue colour of the mixture is estimated with the Lovibond tintometer. If analysed by the spectroscope, the blue mixture shows two absorption-bands at 572μμ and 610μμ respectively (Morton). The blue colour depends only on the intensity of the 610 band.

Greene and Black1 have found that phenol, the cresols, aniline and benzyl-alcohol are suitable for the extraction of free flavin from water.

WITH reference to the recent communication from Prof. Karrer's laboratory1 describing the separation of vitamin A into two fractions by means of calcium hydroxide, we may recall that this separation was effected by us about two years ago2,3, using, however, fuller's earth.

IT has been shown1 that traces of substances like furan, indol and skatol inhibit strongly the intensity of the absorption band of vitamin A with antimony trichloride at 620 mµ. In cod liver oil, there must be such an inhibitor, because after saponification a much stronger Carr and Price reaction is obtained with the unsaponifiable fraction.

INVESTIGATIONS of Evans1 and Karrer2 have demonstrated that α-tocopherol possesses reducing properties, so that it can be determined by potentiometric titration with gold chloride.

KOSCHARA1 has demonstrated the presence of flavins in urine, and has been able to isolate a crystalline flavin (uroflavin). I have carried out an investigation to determine if large doses of flavins (ox liver), similar to vitamin C (Harris2 and van Eekelen3) and B1 (Harris4), caused an increased urinary output.