SOME CONTEMPORARY ADVANCES IN PHYSICS III 205 



since this Rraph was piiblislicd, and in Fig. 11 I have set down all the 

 exp)erimontal \aliies known tt» me which ha\'e been given for excita- 

 tion-fK>tenlials of the first eight elements, omitting those which are* 

 so small that they obviously do not belong to the K class.'" The 





Fig. 12 — Emission-frequencies of heavier and excitation-potentials of lighter elements, 

 correlated with L electrons. (Proceedings of the Royal Society.) 



^ The data are from various sources, as follows. The dots for hydrogen and 

 helium represent the observed ionization and resonance potentials of these atoms. 

 The dots for Be, B. C, N and O arc at values of excitation-potentials given by Mohler 

 and Foote from experiments on gaseous compounds of these atoms. .Ml the other 

 data except Molweck's are values of excitation-[X)tentials for solids. The crosses 

 for Li and Be stand for the excitation-potentials observed by McLennan, the circles 

 for the extraction-potentials of the K electrons which they infer from these data. 

 The cross for B represents three values lying so close together as to Ix indistinguish- 

 able ffrom .McLennan, Hughes, and Moltsmark) and the cross for C also three 

 coincident values (Kurth, Richardson and Baz^oni, HoliveckV The circle for B 

 is at the potential corresponding to a discontinuity in absorption, observed by 

 Holweck. The triangle for C is a value observ-ed by Hughes, and the cross for a 

 value from Kurth (obtained with oxidized copper). No data for for iV« are avail- 

 able. .At .V(i measurements on the wave-length of Ka and at Mg measurements 

 on the K absorption-edge commence. 



