344 CARL VOEGTLIN 



treatment, an observation which these observers consider as a possible 

 explanation of the therapeutic effect of radium upon neoplasms. 



Cooper and Funk (1911) discovered that the active substance is 

 precipitated by phosphotungstic acid, and that the precipitate thus ob- 

 tained yields a highly active preparation after decomposition of the pre- 

 cipitate and removal of the phosphotungstic acid. Later work by Funk 

 (1912, 1913) then showed that this preparation can be further purified 

 by treatment with silver nitrate and baryta, which precipitates the vitamin. 

 By repeated recrystallization of this fraction (pyrimidin fraction), a sub- 

 stance was obtained which melted at 233 C. to which Funk gave the 

 formula C 17 H 20 O 7 N 2 . The crystals, for unknown reasons, very often 

 lose their physiological activity on recrystallization from water, a fact 

 which has been most troublesome in the isolation of. this vitamin. The 

 principal observations of Funk were confirmed by Edie, Evans, Moore, 

 Simpson and Webster (1911-12), Cooper(a)(&) (1913), Vedder and 

 Williams (1916), Williams (1916), Voegtlin and Myers(d) (1920), and 

 others. The last two investigators carried the purification a little further 

 by the use of mercuric sulphate, and obtained a product free of purins, his- 

 tidin, proteins, albumoses arid lipoids. Suzuki, Shinamura and Odaki 

 (1912) claim to have prepared a picrate of the antineuritic vitamin, but 

 their work could not be verified by Drummond and Funk (1914). Hof- 

 meister(a) (d) (1918, 1920) claims that the antineuritic vitamin belongs 

 to the pyrimidin series (CgH^NOs) and that it yields a crystalline hydro- 

 chlorid and gold salt. Williams and Seidell (1916) obtained adenin from 

 autolyzed yeast, and found that it had powerful curative properties when 

 tested on polyneuritic birds. The sample lost its physiological properties 

 on standing. They furthermore found that inactive adenin submitted to 

 treatment with sodium ethylate assumed antineuritic properties, observa- 

 tions which led these authors to regard the antineuritic vitamin as an 

 isomer of adenin. However, Voegtlin and White (1916), and Harden 

 and Zilva(a) (1917) were unable to confirm these observations. 



The active preparations and crystalline fractions hitherto obtained 

 by various workers are probably mixtures of active material and im- 

 purities, and the passing over of the active substance into certain fractions 

 is explained by Drummond (a) (1917) by the assumption that this vitamin 

 is easily carried down by bulky precipitates. The antineuritic vitamin is 

 adsorbed by charcoal (Chamberlain and Vedder(a) (6), 1911), by fullers' 

 earth (Seidell, 1916), by mastic emulsion or basic ferric phosphate (Voegt- 

 lin and Myers(rf), 1920), and by colloidal ferric hydroxid (Harden and 

 Zilva(c), 1918). Of these absorbing agents, fullers' earth appears to be 

 the most suitable one for the purpose of preparing a quite stable concen- 

 trate from aqueous solutions containing this vitamin. The activated 

 fullers' earth can be made use of as a source of this vitamin in feeding 

 experiments (Eddy, 1916). Adsorbing agents have so far not been of 



