•XI. A. 2 Williams: Chemistry of the Vitamines .g3 



pared with about 450 grams obtained by Funk ^* from the same 

 ■quantity of polishings. This large yield is somewhat, but not 

 greatly, reduced if the original extract is made with neutral 

 alcohol and the concentrated extract hydrolyzed by boiling with 

 10 per cent sulphuric acid under a reflux condenser for five 

 hours. However, the maceration in acid alcohol produces ah 

 extract which cures neuritic fowls in doses corresponding to 

 50 grams, whereas extracts made by the latter method must 

 •be given in doses corresponding to 100 grams to produce the 

 same result. 



The mass of dry phosphotungstates is ground intimately with 

 two and a half times its weight of barium hydroxide. During 

 this process the mixture becomes pasty and develops an evanes- 

 cent green. The odor evolved is somewhat distinctive and re- 

 sembles that of methyl amine. The pasty mass is collected in 

 a large bottle and is shaken with 3 liters of water for five 

 hours and filtered. The residue is again shaken twice with 

 .water for an hour each time. The combined filtrates, from 

 which in the meantime the excess of barium hydroxide has 

 been completely removed with sulphuric acid without the least 

 unnecessary delay, are now carefully tested for excess of sul- 

 phuric acid or barium. Any excess of either having been care- 

 fully removed, the solution is neutralized with nitric acid, using 

 litmus paper as indicator, and is concentrated in vacuo to a 

 volume of about 1 liter. At this point the toxic properties 

 of the liquid are so great that it is impossible to demonstrate 

 its curative power. 



To the concentrated liquid a 10 per cent solution of silver 

 nitrate is added till no further precipitation occurs. The bulky 

 yellow precipitates of purine bases are separated by filtration, and 

 the filtrate is reserved for further fractionation. The purine 

 bases are discarded. I am yet uncertain whether or not Funk 

 carried out this separation of the purine bases. in the case of 

 rice polishings, although he reports having done so with yeast. 

 At all events the purine bases so separated, although consider- 

 .able in amount, do not when freed from silver possess curative 

 properties to a high degree. Moreover it would be quite hopeless 

 under my conditions of work to try to insolate any substance 

 in a pure state from the vitamine fraction if the purines were 

 .included with it. 



-; A small aliquot part of the filtrate from the purin^e bases is 

 •titrated with a 5 per cent silver nitrate solution till a. drop ojf 



"Joum. Physiol (1912), 43,. 396. * " ^"^ 



