188 THE VITAMINES 



ation, if a large quantity of inactive extractives did not go into 

 solution at the same time. If the phosphotungstic acid precipitate 

 from autolyzed yeast is treated directly with dry acetone, almost a 

 third of it remains insoluble, including a large amount of purine 

 derivatives. If the acetone-water method is used, as outlined above, 

 we obtain from the above-mentioned precipitate, weighing 1125 

 grams, the following fractions: 



Total precipitate 1125 grams. 



Insoluble residue 150 grams = 13.3 per cent. 



This method might be of importance but in this case, no animal 

 experiments were carried out. 3 



A method indicative of great progress at the time was described 

 by Seidell (495). If, for example, 1 liter of autolyzed yeast is shaken 

 with 50 grams of Lloyd's reagent (fuller's earth), allowed to stand for 

 several hours and the residue filtered off and washed with dilute 

 hydrochloric acid, vitamine B is quantitatively removed from the 

 solution, and the filtrate is completely inactive. The great hopes 

 held out for this method, however, have not materialized. In the 

 first place, it is very difficult to remove the vitamine from the fuller's 

 earth, and secondly, a number of other substances, difficult to remove, 

 are adsorbed together with the vitamine. In the end, R. R. Williams 

 and Seidell (496) were able to extract the vitamine from the fuller's 

 earth with 5 per cent sodium hydroxide, at the same time showing 

 that the vitamine was contaminated with considerable adenine. 

 Osborne and Leavenworth (496a) showed that dilute alkali has 

 no destructive action of vitamines, especially if the contact is of 

 short duration. For liberation of vitamine from activated fuller's 

 earth all those methods are suitable which are used in freeing alkaloids 



3 In the meantime, this method was elaborated by Drummond (494) in 

 that he investigated the solubility of various phosphotungstates, and dis- 

 cussed the practical applicability of these data. 



