744: _ Prof. Townsend and Mr. Hurst on the 
> . e 
Hydrogen, 20 mms. pressure. 
AR Sa tate a “4. 5 | 6 | 
Pac WOH. en, hk ten 12°7 318 913 495 
Aa pits eee hae 317 91-0 495 | 
The agreement between the values of the currents g found 
experimentally and the numbers n given by the formula 
(a—)<o-*™ | 
oa Bea=Bid shows that the theory affords a satisfactory 
explanation of the currents which are produced before 
sparking occurs. 
The accompanying curves (fig. 1) give the connexion 
between B and - for the smaller values of the variables. 
The corresponding curves for the larger values of B and the 
values of ~ are to be found in the previous researches which 
have been published on this subject. 
aaa Adee 
WEPAME BEES ioe 
f prEres 
wa dia 
200 
The values which have been found for the quantity 8 saow 
that the positive ions in hydrogen are more active in producing 
ionization by collision than the positive ions in air. This is 
due partly to the fact that the free paths of the ions are 
longer in hydrogen than in air, but itis impossible to account 
7005 
