194 THE VITAMINES 



reasoning pursued by Williams could not be confirmed, and since 

 he has published no further related work since 1916, the subject may 

 apparently be considered as closed. 



STABILITY OF THE ANTIBERIBERI VITAMINE AGAINST HEAT AND 

 CHEMICAL AND PHYSICAL AGENTS 



As far back as the work of Grijns (I.e. 52) we knew that the 

 vitamine B from Katjang-idjoe beans lost its curative properties on 

 heating to 120 C. Ever since, a number of investigators have 

 occupied themselves with this problem. It was soon evident that 

 the stability was dependent upon a number of factors. Among these 

 was the vitamine content of the starting material used, the chemical 

 reaction of the substrate and the duration of the heating period. 4 

 Although these points are of great practical importance as regards 

 the etiologic and dietetic significance, they are only of moderate 

 theoretical interest, so long as the vitamine itself has not been pre- 

 pared in the pure state and its characteristics determined. Only 

 then shall we be in a position to conduct such experiments exactly. 

 From the description of the isolation experiments, it is clear that this 

 vitamine is quite stable and can withstand a number of chemical and 

 physical manipulations. Therefore, it is hard to determine at which 

 stage of the work this substance loses its activity. In the fraction- 

 ation, there is very little loss of activity till we come to the last 

 stages, where it decreases rapidly. One almost has the impression 

 that the substances accompanying the vitamine serve to stabilize it. 

 We must admit that we are still in the dark as to the cause, and 

 although this may eventually find quite a simple explanation, it 

 seems to us for the present remarkable and mysterious. 



As regards the solubility of vitamine B, this has already been 

 spoken of in the preceding pages. All investigators apparently agree 

 that this substance is insoluble in strong alcohol. There are also 

 some experiments which indicate that prolonged boiling in alcoholic 

 solution may inactivate this vitamine. As to the effect of heat, the 

 findings vary ; similarly, with the effect of alkalis. On the other hand, 

 the investigators are one in stating that this vitamine is very resistant 

 to acid. Among other chemical reagents, diazotization, according to 



4 Emmett and Luros (I.e. 94) give a good bibliography relative to this 

 question. 



