CHAPTEE XVIII 



MODELS OF POSITIVE ION OR ATOMIC NUCLEUS 



Fluorescence of monatomic gases — Effect of specific inductiye 

 capacity on molecular aggregation — Difficulties in the 

 kinetic theory — Nature of positive nucleus — Effect of 

 approach of corpuscles on motion in nucleus — Balmer's law 

 — Eamage's observations — Transmutation of the elements 

 of same series — Aggregations produced by pressure — 

 Models of molecules in phosphorescent gases and in eman- 

 ations. 



The fluorescence of the monatomic gases presents 

 a striking anomaly in many respects, and opens 

 up many new lines of thought and investigation. 

 It was hoped that experiments upon this phenom- 

 enon would help to elucidate, in some degree 

 further, some of the problems which bear so closely 

 upon these questions, but still remain unsolved. 



In dealing with them it is worthy of note that 

 helium is found in smaU quantities in many 

 fluorescent substances, such as compounds of 

 uranium, yttrium, tungsten, zirconium, thorium, 

 etc., and it seemed quite possible that the gas 

 might exhibit phosphorescence when subjected to 

 the influence of ultra-violet light. Helium is one 

 of the most phosphorescent of all gases under the 

 influence of the electric spark. 



