1909.] 



Yeast-juice from Hexose and Phosphate. 



533 



All these acids were prepared from the lead salts with sulphuretted 

 hydrogen, excepting No. 13 which was obtained from the barium salt by 

 means of dilute sulphuric acid. No. 16 was obtained from yeast-juice to 

 which neither sugar nor phosphate had been added, whilst zymin was 

 employed for the preparation of Nos. 6 and 11. 



It will be observed that the differences between the values for the acids 

 derived from fructose and mannose are of the same order as the differences 

 among the glucose preparations themselves. With so low a rotatory power 

 a small experimental error or a trace of optically active impurity would 

 cause an appreciable difference in the u^, and the differences seen in the 

 table are probably due to these causes. The rotations of the barium salts of 

 these acids, which are slightly soluble in cold water, were also determined, 

 and were found to be approximately equal. These are given in Table IV. 



Table IV. 



Origin. 



Grammes per 

 10 c.c. 



Rotation in 

 4 dm. 

 + 



« D l7°-5. 



+ 





-0665 



-085 



3 -20 





-0692 



0-088 



3-18 





-0656 



0-082 



3-13 



Hydrolysis of the Acid. 



(a) Production of Phosphoric Acid and a Lcevorotatory Reducing Substance. — 

 When the solutions of the acid were boiled, phosphoric acid was gradually 

 set free, the reducing power to Pavy's solution increased, and the solution 

 became laevorotatory. Table V shows the rate at which the first two 

 of these changes took place when a solution of hexosephosphoric acid 

 prepared from glucose was boiled in a flask fitted with a reflux condenser. 



The phosphoric acid is expressed as grammes of magnesium pyrophosphate 



Table V. 



Time, in hours. 



Free phosphate. 



Reduction. 











0-258 



2 



0-167 



0-297 



4 



0-238 



-342 



7 



0-304 



0-371 



11 



0-365 





15 



0-401 



0-373 



27 



0-467 



0-371 



VOL. LXXXI. — B. 2 Q 



