ABSTRACTS 



321 



Fig. 2 



shortest wave-length of the L X-ray series of this element. A value 

 of 6.7 volts was deduced as the quantum equivalent of La for lithium. 

 The apparatus used was probably not sufficiently sensitive to bring 

 out this critical potential. 



Beryllium 



With beryllium critical potentials were obtained at 16 and 20.3 

 volts. As these values are approximately in the ratio 20 : 27 they 

 were interpreted as representing the first two members of the L 

 series for beryllium. On this interpretation the quantum equivalent 

 of the shortest member of the L X-ray series of beryllium would be 

 about 28.8 volts. 



Boron 



For boron critical potentials were observed at 23.45 and 27.92 

 volts and these were taken to represent the first two members of 



21— c 



