﻿Emission of Positive Thermions from Salts. 



139 



My very best- thanks are due to Prof. 0. W. Richardson 

 for suggesting this investigation and for advice throughout 

 the whole of it. I also wish to thank Mr. C. Bol for care 

 exercised in constructing the glass parts of the apparatus, 

 and Mr. E. Keil and Mr. W. Durvea for their careful 

 construction of the metal parts. 



Appendix. 



Since the completion of the experiments described above 

 a series of determinations has been made of the specific 

 charge of the positive thermions from zinc sulphate. Of 

 several salts of zinc tested the sulphate alone gave reliable 

 curves. The results of the measurements on this salt appear 

 to confirm the rule which has been found so far to be general, 

 that the positive thermions are single atoms of the metal of 

 the salt minus single electronic charges. The data follow: — 



Zinc Sulphate. 



V. 



11. 

 2915 



cL 

 1-295 



2x. 



e/m. 



282 



•3G8 



179 



282 



2915 



] -295 



•368 



179 



282 



2915 



1-295 



•375 



186 



481 



2915 



1-295 



•263 



157 



i 



(«A*)zn(++) i («/™)zn(+) 



297 



148 



XI. The Hole Played by Gases in the Emission of Positive 

 Thermions from Salts. By Clinton J. Davissox, B.S., 

 Fellow in Physics, Princeton University. Princeton, A. J., 



U.S.A.* 



IN the preceding paper the author has adduced experimental 

 results which show that the positive thermions from salts 

 of the alkaline earths in air at pressures under 10~ 4 mm. of 

 mercury are— ^excepting those that apparently arise from im- 

 purities — single atoms of the metals of such salts minus single 

 electronic charges. This result, it has been pointed out, is in 

 accord with that obtained by Richardson in similar experiments 

 upon the positive thermions from salts of the alkali metals. 

 Although, from the nature of the experimental method and 

 from the results, there can be little doubt as to the validity 

 of the main conclusions arrived at in tiiese investigations, it 

 may not be said that they dispose of all other hypotheses 

 which have been entertained up to the present time regarding 

 the nature of this class of ions. It may not be said- for 





Communicated bv Prof. 0. W. Richardsou, 



