Funk (1) made the first elaborate effort to isolate and identify the anti-beri-beri vitamin. He found that alcohol would extract a part of the physiologically active substance from rice polishings but that water was a far more effective solvent. From such solutions it can be precipitated by phosphotungstic acid or by silver nitrate and barium hydroxid, and also partially by mercuric chlorid. By means of the systematic procedure ordinarily employed for the separation of mixtures of organic bases, Funk established the fact that the curative substance contains nitrogen and is free from phosphorus. He believed at one time that he had definite evidence that it belonged to the class of organic compounds known as pyrimidins.

It has been the experience of all investigators that the farther the substances possessing curative properties are purified, the less effective they become. This suggests that the important substance sought is not a crystallizable body, and that the crystals of definite and identifiable compounds thus far obtained are merely contaminated with the nutritive principle.