18 



OPTICAL ACTIVATION 



TABLE VI. 



1. g. d-acid and 0.0200 g. quinine in 11 ccm. acetophenone. 

 (0.3305 mole aeid and 0.0056 mole quinine per liter). 



Experiment 31. 



* VIA. 



A - x - = 



dx - x 2 x x 

 dt 



dx 



Cm = A-^_ a 



Here it is observed that the velocitv of the reaction increases 

 with .time, reaches a maxium, and then falls off rapidly to 

 nothing ; also that the ratio of the velocity of decomposition to 

 the mean concentration C m of the undecomposed acid behaves 

 in the same way. As should be expected, since quinine is a 

 laevo-rotatary substance, the rate of decomposition of the two 

 isomers is different. At the end of 70 .minutes, when the 

 difference between the percentage decomposition of the two 

 acids is greatest (almost 25 per cent), the velocity of decom- 

 position of the 1- acid is almost double that of the d- acid. 

 The progress of the reaction with time is shown in fig. 2. 



