540 Mr. W. J. Young. Hexosejihosjyhate formed by [July 30, 



standing for a few hours, the solutions were filtered, neutralised with acetic 

 acid and lead hexosephosphate precipitated with lead acetate, washed and 

 dried over sulphuric acid in a vacuum. The mixture to which the phosphate 

 had been added gave 5 03 grammes of lead salt, whilst the other only yielded 

 1/35 grammes. This experiment also shows that yeast-juice itself contains 

 a small quantity of hexosephosphate, and experiments have already been 

 quoted tp show that this compound has similar properties to that formed 

 when phosphate and sugar are added. The same hexosephosphate was 

 obtained by means of zymin in place of yeast-juice as already mentioned, 

 and as in this case the mixture was not boiled before the precipitation of the 

 lead salt, it follows that the salts of this acid were present in the mixture as 

 such, and were not formed from a more complex body by the boiling, which 

 was always necessary when yeast-juice was employed. A hexosephosphate 

 has also been detected in the extract obtained by boiling pressed brewers' 

 yeast with water. 



Molecular Weight of Hexosephosphoric Acid. — The analyses of the salts of 

 this acid gave no information as to its molecular weight, since the same 

 percentage composition would be obtained if the acid had the formula 

 C3H 5 2 (P04H2) and not CeHioO^PCUH^V The first compound might be 

 expected on hydrolysis to yield glyceraldehyde or dioxyacetone, and these 

 might polymerise to form hexoses ; so that the fact that fructose was formed 

 when the acid was hydrolysed does not do away with the possibility of the 

 smaller formula. 



As no derivatives of the acid could be obtained, such as a hydrazone or an 

 osazone, analysis of which would have settled the question, recourse was 

 made to physical methods. The molecular weight of the acid was calculated 

 from the difference between the freezing point of its solution and that of 

 water, and was compared with that calculated by taking into consideration 

 the extent to which it was dissociated in solution as determined by the rate 

 at which it hydrolysed cane sugar. The freezing points of three solutions of 

 different concentrations of the acid prepared from glucose was found by the 

 ordinary method, the amount of acid in solution was estimated by titration 

 and checked by the total phosphorus content, and the weight of water in the 

 solution was obtained from the specific gravity. By way of comparison with 

 a compound of known constitution and of a similar nature, corresponding 

 determinations were carried out with a sample of synthetical glycero- 

 phosphoric acid, which was purified by means of its lead salt in exactly the 

 same manner as the hexosephosphoric acid. The results are given in 

 Table XII, Nbs. 1, 2, and 3 being those obtained from the hexosephosphoric 

 acid, and Nos. 4 and 5 from two concentrations of glycerophosphoric acid. 



