SELIG HECHT 



11 



In a few tests the procedure was slightly varied. Two sets of tubes 

 were run. In the one the readings were made intermittently, there 

 being about seven interruptions in the exposure. In the other, the 

 readings were also made intermittently, but with only two or three 

 interruptions in the exposure. The results in the two cases were the 



O /O 20 30 



txposure^- r)/nufes 



Fig. 5. A comparison of the effects of intermittent (black rectangles) and 

 continuous (white rectangles) illumination on the velocity of decomposition. 

 The black rectangles are from a single tube of visual purple. Each of the white 

 rectangles represents a separate tube. Experiments 32 to 38 inclusive; intensity, 

 53 meter candles; ^ =0.037. 



same within the limits of the experimental error. It may therefore 

 be safely concluded that there are no aberrant factors such as an in- 

 duction period or an after effect operating in these experiments. 



It will be remembered that these results are to be expected on the 

 basis of Talbot's law for the fusion of successive light flashes. In such 



