VELOCITY OF REACTIONS 



31 



by Hudson, who observed that the glucose formed 

 during the beginning of the process shows the 

 phenomenon of mutarotation, and that its quantity 

 therefore cannot be determined immediately with the 

 aid of a polarimeter, as Henri had done. In order 

 to eliminate the mutarotation it is necessary to add 

 some trace of alkali before the polarimetric deter- 

 mination. This is made very evident by the 

 following figures of Hudson, and diagram, Fig. 5. 



As is easily seen from the figures and Fig. 5 the ex- 

 periments in which the mutarotation was eliminated 

 by addition of a trace of alkali give a fairly good 

 constant (mean value 542- io -5 ), whereas the figures in 

 the fourth column, representing the observed rotation 

 without addition of alkali, give a steadily increasing 

 value. As early as 1890 O'Sullivan and Tompson 

 had recognized the error caused through mutarota- 

 tion, and their measurements, which had fallen into 

 oblivion, have been verified by Hudson. 



Not only the mutarotation exerts an influence on 



