1909.] Yeast-juice from Hexose and Phosphate. 5 £3 



If, on the other hand, the compound have the smaller formula, with a 

 molecular weight of 170, it will be a dibasic acid and the solution will 

 contain 50 molecules to every 100 contained in a solution of hydrochloric 

 acid of similar normality. The number of dissociated molecules corresponding 

 to the hydrogen ions present will be 17'7, yielding 17'7 x 2 = 35'4 ions, 

 50 — 17'7 = 32*3 will be undissociated, and the total number of units will be 

 35 - 4 + 32 - 3 = 67"7. The molecular weight, as deduced from the freezing point, 



would therefore be 17 ?? * 50 = 125'5. 



67-7 



The observed depression thus corresponds more closely to that which would 

 be expected from the larger formula, although the agreement is not so good 

 as that in the case of glycerophosphoric acid. This low result may be due to 

 some hydrolysis in the solution, which would make the number of units still 

 greater. If the hexosephosphoric acid had the smaller formula, it would be 

 expected to depress the freezing point at least to the same extent as glycero- 

 phosphoric acid, since it only differs from this by two hydrogen atoms, and 

 is slightly more dissociated in solution than this acid. These results thus 

 point to the acid having the formula CeHioO^PC^H^. 



Further evidence against the acid being a derivative of glyceraldehyde is 

 also afforded by the following facts : — When the acid was reduced with 

 sodium amalgam, no glycerol was obtained, as might have been expected if 

 it were a compound of glyceraldehyde. When glycerophosphoric acid was 

 heated with hydriodic acid in a current of carbon dioxide, it was reduced to 

 isopropyl iodide, which was detected by passing into alcoholic silver nitrate in 

 the manner in which glycerol is estimated by the method of Zeisel and 

 Fanto. On the other hand, hexosephosphoric acid gave no volatile iodide 

 when treated in this manner. 



Constitution of Hexosephosphoric Acid. — It has not yet been found possible 

 to obtain any evidence with regard to the position of the phosphoric acid 

 groups in the molecule. The facts that the compound does not reduce 

 Fehling's solution in the cold until after a long time, and that no hydrazones 

 or osazones could be obtained, render it possible that the acid does not contain 

 an active earbonyl group, and it may be that this group is involved in the 

 reaction with the phosphoric acid. 



Glucose, fructose, and mannose all appear to yield the same hexose- 

 phosphoric acid when fermented by yeast-juice in the presence of phosphate. 

 One explanation of this is that these sugars are changed, before conversion 

 into hexosephosphate, into some form common to all three. The only 

 differences between glucose, fructose, and mannose are in the groups or 

 arrangement of the groups attached to the first two carbon atoms : 



