220 



COMPTON— ARC SPECTRA AND 



larger one for strong effects), the interpretation of each of the critical 

 potentials is as shown in Table I. Setting in of new effects produces 

 a change in curvature of the curves of Fig. 6. Such changes do not 

 necessarily indicate new effects, however, and the effects may not be 

 shown prominently at exactly the same voltage as in Fig. 5. Some 

 caution is needed, therefore, in interpreting the curves in cases which 



Accelerating Potential lu Volts 



Fig. 5- 



correspond to weak effects. We believe, however, that a considera- 

 tion of the full set of curves points unmistakably to the following 



results : 



TABLE I. 



As an example of the method of interpretation, consider the 13.6 

 volt effect. The R (on)// (on) curve indicates that it is due to 

 ionization. The / (on)// (off) curve indicates that it is due to the 



