THE ANTIBERIBERI VITAMINE 177 



have often tried to precipitate the vitamine with gold chloride but 

 without succeeding. Besides, as we have lately again noted, a num- 

 ber of substances including nicotinic acid, are precipitated by bismuth 

 potassium iodide. According to Efofmeister (I.e. 4,83) colamine, 

 proline, hematine, papaverine, trigonelline and stachydrine have no 

 influence" on beriberi in pigeons. We have tried the above pro- 

 cedure with tomatoes but found it impractical. 



CHEMICAL INVESTIGATION OF YEAST 



The chemical aspect of vitamine B has been neglected in most of 

 the books and reviews on the subject. We propose to describe only 

 the indisputable facts in order to give the reader the opportunity of 

 forming his own opinion of the status of the question. It is too 

 soon to say whether the isolation of this vitamine has been successful 

 or not. In any case, the investigation on yeast extract made by us 

 is one of the few researches upon which we may build further. We 

 have investigated yeast in various ways, and yet we do not know if 

 the vitamine occurs free or combined. The facts uncovered up to 

 the present point to both possibilities. 



In our first attempt to isolate the vitamine from yeast (I.e. 324), 

 75 kilos of dried yeast were extracted with alcohol, the extract con- 

 centrated in vacuum and the residue hydrolyzed with 5 per cent 

 sulphuric acid for five hours; after cooling, it was filtered from 

 separated fatty acids, the filtrate diluted with an equal volume of 

 water and precipitated with phosphotungstic acid. The precipitate 

 was decomposed in the usual manner, and the resulting filtrate con- 

 centrated. A concentrated watery solution of silver nitrate was then 

 added till a drop of the clear solution gave, with a saturated baryta 

 solution, instead of a white precipitate, a brown precipitate of silver 

 oxide. The solution, freed from the heavy precipitate of purine 

 bases, was treated with saturated baryta so long as it gave a white 

 precipitate with ammoniacal silver nitrate solution. The silver 

 precipitate was decomposed with hydrogen sulphide and the filtrate, 

 after the removal of the last traces of baryta, concentrated to small 

 volume in vaccum; the residue was transferred to a dish with a little 

 alcohol and allowed to stand in the dessicator, whereupon crystals 

 separated out weighing 0.6 gram. They were recrystallized from 

 dilute alcohol yielding 0.45 gram of colorless needles (see fig. 40) 



