THE ANTIBERIBERI VITAMINE 193 



tion of lead, the filtrate was precipitated by an excess of silver acetate 

 and treated with baryta, after removal of purine precipitates. 



Steenbock (507) prepared from egg-yolk a substance soluble in 

 water-acetone, active and not quantitatively precipitated by phospho- 

 tungstic acid. McCollum and Simmonds (I.e. 315) sought to con- 

 centrate vitamine B by extraction with various organic solvents. 

 They found that beans could be extracted with ether, benzol, or 

 acetone, without dissolving the vitamine. Subsequently it can be 

 extracted with alcohol and the solution, when concentrated, may be 

 taken up by benzol. The same method was applied to wheat germ 

 and pigs' liver. 



SYNTHETIC EXPERIMENTS 



Although we undertook some synthetic experiments with nicotinic 

 acid, based on its occurrence in the vitamine fractions obtained from 

 various sources, we perceived that theoretical reasons for this trend of 

 thought were hardly justifiable. Nevertheless, Williams (I.e. 473), 

 instituted such experiments. He condensed p-oxy nicotinic acid with 

 itself or with nicotinic acid, and believed that the first condensation 

 product was much more active for avian beriberi than all other 

 similarly synthesized condensation products. Thereupon, Williams 

 (508) proposed the very attractive theory that oxy-pyridine and 

 pyridine carbonic acid occur in two isomers, which possess different 

 crystalline forms, and which may be transformed into each other 

 under certain conditions. The labile form remained intact for some 

 days and in this case was therapeutically active; then it changed into 

 the inactive stable form. Later, Williams (509) extended his theory 

 to include such pyrimidine and purine derivatives as were theoreti- 

 cally capable of forming the betaine ring. Williams and Seidell (I.e. 

 496) tried to convert adenine obtained from autolyzed yeast by ad- 

 sorption with fuller's earth, by boiling with acetic acid and acetic anhy- 

 dride, into an isomeric form. This labile form was supposed to have 

 a therapeutic action; after recrystallization, this peculiarity was sup- 

 posed to disappear, the substance being changed back again to the 

 usual adenine. The theory of Williams explained the slight stability 

 of vitamine B very beautifully, but unfortunately it could not be con- 

 firmed. Voegtlin and White (I.e. 497) sought in vain to produce an 

 active product from adenine, while Harden and Zilva (510) tried to 

 do the same with o-oxypyridine and adenine. Since the course of 



