534 Mr. W. J. Young. Hexosephos-phate formed by [July 30, 



and the reduction as the number of grammes of glucose to which it 

 corresponded. The original solution contained 07167 gramme of the acid 

 in 200 c.c. (approximately - 01 molar), corresponding when completely 

 hydrolysed to 0-511 gramme of magnesium pyrophosphate, and equivalent 

 to 0-414 gramme of glucose. Samples were taken out after the intervals 

 stated, and the free phosphate estimated with magnesium citrate mixture 

 and the reducing power with Pavy's solution. 



The solution after about seven hours' boiling became very dark coloured, 

 some of the reducing substance formed evidently being decomposed. 



The acids obtained from fructose and mannose behaved in a similar 

 manner on boiling, in every case a l?evorotatory substance and phosphoric 

 acid were formed. The following Table VI gives a number of examples of 

 this change in rotation on the hydrolysis, at 100°, of the compounds prepared 

 from all three sugars and, in one case, No. 6, of that obtained from yeast- 

 juice to which nothing had been added. 



Table VI. 



No. 



Origin. 



Glucose . . , 



„ 



Fructose .. 

 Mannose .. 

 Yeast-juice 



Time of boiling, 

 in hours. 



Kotation in 4-dm. tube. 



Before. 



+ 



After boiling. 







O 



6 



0-161 



0-299 



11 





0-558 



14 





0-658 



10 



0-634 



0-756 



6 



0-543 



0-924 



10 



0-416 



1 -514 



6 



0-230 



0-204 



16 



0-074 



-500 



As glucose is converted hy alkalis into a lsevorotatory mixture of 

 glucose, mannose, and fructose, it was thought that the treatment with 

 alkali in the separation of the free phosphate, during the preparation of the 

 lead salt, might have altered the hexosephosphate in such a manner as to 

 account for the lasvorotatory sugar being obtained on hydrolysis. Prepara- 

 tions of the lead salt were therefore made without removing the free 

 phosphate, the solution being kept always slightly acid, but the method 

 being otherwise the same as before. The hexosephosphoric acids obtained 

 from these acid preparations were found to have approximately the same 

 specific rotatory power as the others. The strength of the solution used was 

 estimated by determining the total phosphorus, and making allowance for 

 the small quantity of free phosphoric acid, which was precipitated in 



