Ionic Mobilities in Hydrogen. 



Table III. 

 Negative Ion B. 



343 



Press. 



E. 



1 u. 



I l/«- 



Press. 



E. 



u. 



i/u. 



cm. 



volts. 



cm./sec. 





CLO. 



volts. 



cm./sec. 





8-6 



33 



139 



•0072 



*56-0 



195 



23'4 



0426 



18-4 



70 



65-3 



•0153 



58-3 



220 



20-8 



•0481 



23-5 



37 



52-1 



•0192 



60-6 



230 



19-9 



•0503 



24-4 



94 



48-7 



•0206 



63-5 



244 



18-7 



•0534 



26-3 



97 



471 



•0212 



*68-4 



255 



18-0 



•0557 



36-3 



138 



33-1 



•0302 



*7M 



232 



19'7 



•0507 



39-3 



63 



31-0 



•0323 



*75-5 



230 



19-9 



•0503 



41-3 



159 



28-8 



•0348 



764 



137 



15-7 



•0f>36 



*49-8 



176 



26-0 



•0385 



77-5 



126 



15-1 



•0645 



513 



194 



236 



•0424 











Mean v;ilue Pxw = 1206 



* The asterisks in the Tables indicate those values which are plotted 

 but were excluded from the calculation of the mean value of Pu. 



Table IV. 

 Negative Ion C. 



Press, 

 cm. 



E. 



volts. 



u. 



cm./sec. 



\/u. 



PXM. 



3010 



56-0 



85 



53-8 



•0186 



67-7 



100 



45-7 



•0218 



3105 



75 - 4 



113 



40-5 



•0247 



3054 



Mean value Px^=3084 



Discussion. 

 In fig. 4 the reciprocal of the mobility is shown plotted 

 against the pressure for all the ions. The values from the 

 tables are marked by darker rings. For the sake of com- 

 parison, the values of Chattock t and of Franck J and Pohl 

 are marked by crosses with initials (atmospheric pressure). 

 The differences in my values indicate that purifying the gas 

 has the effect of making the positive ion less mobile and the 

 negative ion more mobile. A similar result is noted by 

 Wellisch § for the ions in air when the drying is very 

 thoroughly carried out. 



t Chattock, Phil. Ma?. 1899, ser. 5, vol. xlviii. p. 401, and 1901, ser. 6, 

 vol. i. p. 79. 



X Franck & Pohl, Verh. d. Deut. Phys. Ges. 1907, p. 69. 

 § Wellisch, Amer. Journ. Sc. May 1915. 



