﻿182 Charges on Thermions in Air and Hydrogen. 



nichrome thin enough, and larger currents were necessary 

 than could be carried for any great length of time by some 

 o£ the leads in use. Then, too, it was found difficult to weld 

 the nichrome and it was soldered to copper leads directly, 

 with the same results as in the case of platinum, the solder 

 fused with the nichrome so that but few few readings could 

 be obtained from one strip, and it was uncertain whether the 

 ionization was due entirely to the nichrome or partly to the 

 heated solder. 



In the early stages of the experiment some doubt was felt 

 as to whether these double charges might not be due to two 

 ions, each with a single charge and each carrying along a 

 load of air particles sticking together after being given off 

 from the hot metal, and Millikan's * recent work did seem to 

 make this worth considering. However, the fact that the 

 number of these double charges depends entirely on the 

 temperature of the strip and not at all on the temperature 

 of the gas in the testing-chamber makes it seem highly 

 improbable. 



"With the idea of confirming, or otherwise, these results 

 some experiments on the velocity of ions from the same 

 source were -undertaken but are not yet ready for publication. 

 This much, however, may be said. The maximum velocity 

 was found not to vary with the temperature of the wire,, but 

 Rutherford \ found that the average and minimum velocities 

 decreased with increase in the temperature of the wire. This 

 is in accord with the theory worked out by W 7 ellisch \ if we 

 assume that at high temperatures some of the ions carry 

 charges %e rather than e, for his theory would lead to the 

 conclusion that a particle carrying a charge e would have a 

 greater mobility than one carrying a charge 2e. 



In conclusion I want to express my thanks to Prof. 0. W. 

 Richardson for suggesting the experiment, and for the advice 

 given me from time to time during its progress. 



I wish also to thank Mr. C. Bol for advice and help with 

 the mechanical details. 



* R. A. Millikan and II. Fletcher, Phil. Mag. June 1911, p. 753. 

 t E. Rutherford, Phys. Rev. xiii. p. 321 (1901). 

 X E. M. Wellisch, Phil. Trans. A, vol. ccix. p. 249. 



