508 



Mr. W. B. Haines on Ionic Mobilities 



through a charcoal bulb cooled in liquid air. Using the 

 same method of continuous flow, the experiments were at 

 once successful in indicating negative ions of high mobilities 

 in Ivydrogen. The same results were obtained from hydrogen 

 prepared by electrolysis. A careful repetition and analysis 

 of the curves obtained with varying degrees of purity show 

 the following results. 



For hydrogen dried but not otherwise purified, the values 

 were: negative w = 7*4 cm./sec, positive w=6*0 cm. /sec. 

 These are in agreement with the measurements of Franck 

 and Pohl, who give negative u = l'6S, positive w=6*02. 

 When the gas is purified, curves of several different types 

 are obtained, specimens being shown in fig. 5. The normal 



Fisr. 5. 



200 



300 



400 



negative ion has an increased mobility of about 9, and is 

 shown in all the curves (A). The curves numbered 4, 5, 

 and 6 show the free electron at D, giving values of u between 

 37 and 170 cm./sec. Intermediate between A and D there 



