530 Dr. E. F. Armstrong and Mr. E. J. Caldwell. [Apr. 5, 



Table IV. — 18 per cent. (0*5 gramme molecule) maltose, 0-5007 

 gramme molecule HC1. Temperature 60 o, l. 







Per cent. 



J-U -i a, 



-r log 10 



t a — x 



Time in hours. 



aj). 



hydrolysed. 







23°-28 



o-b 





8 



20-02 



23-5 



2-43 



16 



17-92 



38-7 



2-22 



24 



16-12 



51-7 



2-20 



50 



12-58 



77-3 



2-15 



72 



11-22 



87-1 



[2-06] 



96 



10-45 



92-7 



[1-97] 



144 



9-85 





168 



9-95 







216 



9-94 







Complete change 



9-44 







Mean 2 -25 



K = 4-49. 



It will be noted that the values in the last column begin to fall after 

 50 hours, when about three-quarters has undergone change. As the 

 hydrolysis of maltose is carried to an end, the value of a D falls to a 

 minimum, then rises slightly, finally remaining steady ; the theoretical 

 minimum rotation, however, is never attained. This is easily explicable 

 as the consequence of the secondary changes brought about by the 

 action of the acid on the glucose. 



The following table shows at a glance the vast difference in the 

 values of K for milk sugar and maltose as compared with that for 

 cane sugar. This last value has been calculated with the aid of 

 Arrhenius's temperature equation from the 47*6 value at 25° given by 

 Ostwald. 



Table V. 



Sugar. K at 60°'l. Eatio. 



Milk sugar 3*53 1*0 



Maltose 4*49 1-27 



Cane sugar 4378-0 1240-0 



Although it is not yet possible to explain this very striking difference, 

 it must be remembered that cane sugar has a peculiar structure : 

 maltose and milk sugar are closely related in structure, one-half of the 

 molecule still showing the properties of glucose ; but cane sugar has 

 none of the properties either of glucose or of fructose. 



Influence of Concentration of Hydrolyte.- — Whereas, in the case of 

 enzymes, an increase in the concentration of the sugar never increases 

 the rate of hydrolysis, in the case of acids an increase in the concen- 

 tration of the hydrolyte actually hastens the rate of change. This 



