a series 



ABSTRACTS 319 



A. High Range Critical Voltages, and K Series Spectra 



Lithium 



For lithium high range critical potentials were found at 31.8 

 and 37 volts. As these values are approximately in the ratio 27 to 

 32, it was concluded that they represented the first two members 



of a series with a frequency formula y=Al 1 — — ). Such 



would have 42 . 4 volts for the quantum potential of its shortest mem- 

 ber. This voltage was taken to represent the critical absorption 

 wave-length of the K X-ray series of lithium. 



Beryllium 



For beryllium critical potentials were found at 78.2 and 93.0 

 volts. From them the authors deduced 104.3 volts as the potential 

 corresponding to the critical absorption wave-length of the K series 

 of this element. 



Boron 



For this element only one critical potential was found, viz., 147 

 volts, and this has been taken to be the quantum equivalent of the 

 shortest member of the K series for boron. 



Table I contains the critical potentials found for lithium, beryl- 

 lium, and boron. It also contains values found with the photoelectric 

 method by Richardson and Bazzoni, Kurth, Hughes, or Mohler and 

 Foote, for carbon, nitrogen and oxygen. For the elements heavier 

 than oxygen, the values tabulated were taken from "Data relating 

 to X-ray Spectra" (Bulletin of the National Research Council, 

 No. 6, Nov., 1920). The ionisation potentials for helium and hydrogen 

 are also given in the Table. 



