PHOTOCHEMISTRY OF VISUAL PURPLE. 



III. 



1. Altogether I have followed the progress of the bleaching of visual 

 purple in 88 separate experiments. These have been performed under 

 a variety of conditions to which reference will be made in the proper 

 place. Figs. 2, 3, and 4 will serve as examples of what happens. 

 They represent random samples of experiments performed so as to give 





I 



/oo 



80 



60 



^O 



SO 



20 30 ^O 



d'xposure -^/^^inuies 



Fig. 3. Results of Experiment 42. Intensity, 28 meter candles; k =0.028. 



different velocities of decomposition, and are quite characteristic of 

 all the other experiments. 



In the figures the readings are plotted as rectangles, on the assump- 

 tion of an error of 5 per cent in the determination of the concentration, 

 and 1 minute in the control of the exposure. The curves are isotherms 

 of a monomolecular reaction 



k = - log 



/ a — X 



