2 Wellisch — Motion of Ions and Electrons through Gases. 



carrier, the separation between the ions and the electrons 

 remaining throughout clearly marked. 



In the present experiments these results have been extended 

 to other gases ; in accordance with expectation the abnormal 

 mobilit}^ values found by previous investigators for the nega- 

 tive ions in hydrogen and carbon dioxide were shown to be 

 capable of a similar explanation, all anomalies disappearing as 

 soon as the resolution of the carriers into ions and electrons 

 was effected. 



A brief study has been made of the motion of free electrons 

 through carbon dioxide at relatively high pressures ; in addi- 



FlG. 1. 



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tion, the motion of ions through a number of vapors has been 

 investigated. 



A few discussions bearing upon the physical interpretation 

 of the results have been included ; in particular, certain out- 

 standing problems of ionic theory have been specially considered. 



2. Experimental Method and Arrangement. 



A description of the experimental method and apparatus has 

 already been published ; on this account it seems advisable to 

 repeat here only the essential features, reference being made 

 to the previous paper for further details. Moreover advantage 

 will be taken here to enter into greater detail in connection 

 with certain features of the method to which only a brief allu- 

 sion was previously made. 



The method employed in the determination of the mobilities 

 was that devised by Franck and Pohl."^ The ionization vessel 



* Franck and Pohl, Verb. Deutsch. Phys. Ges., ix, p. 69, 1907. 



