288 



PHOTOCHEMISTRY OF VISUAL PURPLE. II 



at five temperatures covering the same interval as the previous three. 

 However, in two other series of experiments performed at three 

 temperatures as before, I obtained a value for Qio = 1.15. 



These four sets of preliminary experiments were carried out by 

 the use of a single tube of visual purple for each temperature. Indi- 

 vidual experimental errors may thus possibly account for the differ- 

 ences between the first two and the last two sets of experiments. 

 Therefore, in order to be thoroughly certain of the results, I per- 

 formed two sets of experiments in which three tubes of visual purple 



TABLE I. 



Temperature and Bleaching of Vistial Purple. 



were bleached simultaneously at each temperature. The velocity 

 constants for the two series are given in Table I together with the 

 temperatures. Each figure is the average of three experiments which 

 agreed among themselves in a way similar to the figures previously 

 quoted for one preliminary experiment. 



IV. 



1 . From these results it will be seen that the change in the velocity 

 constant over a range of 30 degrees is practically nil. Graphically 

 this is demonstrated by Fig. 1 , which presents the details of the second 

 series of Table I. The rectangles are the averages of the experi- 

 mental findings at the different temperatures, whereas the curve is 

 the isotherm of a monomolecular reaction 



^ = - log 



in which the velocity constant has the average value of ^ = 0.032. 

 It is apparent that the points at all temperatures fit the single curve 

 as well as can be expected. 



