16 Wellisch — Motion of Ions and Electrons through Gases. 



The first experiments with this vapor, which was introduced 

 at a pressure of 95"°", gave a normal value (K = -41) for the 

 mobility of the positive ion ; the current-potential curve for 

 the negative carriers (fig. 8) was distinctly abnormal, as it 

 afforded evidence of two types of carriers ; in addition to the 

 normal negative ion (K = -44) there appeared a carrier (a, tig. 

 8) for which K had the value 1-692, which is about four times 

 ag great as one might have reasonably expected for the nega- 

 tive ion and, on the other hand, considerably less than the 

 value corresponding to a free electron. On attempting to 

 repeat the experiment after the vapor had been allowed to 

















, Fig. 8. 







































/ 









/ 



90 



















/ 







/ 



5 





Utro/eufn Ether 









/ 







..$ 



/ 





16 



















i^. 



/ 







iy 























..^y 







t 







S 12 



. 









.<» 







<^ 



5 





/ 



/ 



/ 







6 









-4 



^ 



ff^., 











/ 



J 



/ 













< 



A -C-^ 



^ 



,(>pr 









0' 



5 



f 













_^i 



^/"^ 



<^ 



^c 







a' 



7 



y 











4 



V 



/ 











A^ 















'^/ 



/^ 







^ 



^ 



. 



\ 















\A- 



JLe. 



-^ 



^-e 



--O-* 



^ 



) 















20 



40 



60 



80 



100 



120 140 



Volts. 



remain for about two hours in the vessel, only the normal vakie 

 was obtained for the mobility of the negative ion. 



In the next experiment, after a preliminary evacuation of 

 the vessel, streams of vapor were swept through repeatedly in 

 the hope of removing traces of impurities ; the vapor was finally 

 admitted at a pressure of 1^^'^ and the readings quickly taken. 

 The curve obtained is given in fig. 8 ; the direction of the arrow 

 signifies that the current measurements were made in descend- 

 ing order of potential. It will be seen that this curve shows 

 the presence both of ions and of free electrons ; the ions enter 

 at 80 volts and possess a normal mobility, viz. K = '430. The 

 curve marked 1 was obtained only a few minutes before that 

 marked 2 and it will be observed that the electrons have 

 decayed appreciably during this short interval of time. The 

 third curve was obtained 2f hours after the introduction of the 

 vapor ; there is now only the slightest indication of free electrons 

 while the negative ion has still a normal mobility (K='428). 



