248 Mr. E. Rutherford on the Electrification 



Electrification of Different Gases. 



All the gases which were experimented with could be 

 electrified in the same way as air. A gas-bag was filled with 

 the gas to be tested, and then forced along the electrode as in 

 the case of air, care being taken to allow the gas to run 

 through some time before the rays were turned on, in order 

 to remove the air as far as possible from the generating 

 vessel. 



The amounts of electrification obtained for a given velocity 

 of the gas and intensity of the rays varied with the conduc- 

 tivity of the gas under the #-rays. Gases that have a greater 

 conductivity than air gave more electrification than air. 

 Oxygen and coal-gas gave slightly less electrification than 

 air, while carbon dioxide gave slightly more — the amounts 

 being sensibly proportional to their conductivities. 



The vapour of methyl iodide was tried, which has a very 

 high conductivity — over 20 times that due to air. Only a 

 partial test could be made of it, as sufficient quantity of the 

 vapour was not obtainable. Some of the liquid was placed 

 in the generator (fig. 1), and gently heated to its boiling- 

 point, till the vessel was filled with vapour. The rays were 

 then turned on, and a rapid current of air sent for 3 or 4 

 seconds along the central electrode. The amount of electri- 

 fication obtained was over 5 times the amount from air in the 

 same time. After a few seconds the highly conducting 

 vapour was blown out and the electrification became sensibly 

 that due to air alone. If a current of the vapour could have 

 been sent instead of a current of air, it is probable that the 

 amount of electrification obtained would have been over 20 

 times that of air in the same time. 



The experiments on hydrogen were interesting as bearing 

 on the question of the relative velocity of the conducting 

 particles of hydrogen and air. For a given small weight on 

 the gas-bag the amount of electrification from air was 2*5 

 times that due to hydrogen in the same time. As the weight 

 was increased the ratio fell to 1*5. This is as we should 

 expect if the velocity of the hydrogen ions was greater than 

 those of air. For small velocities of the blast a much smaller 

 proportion of the hydrogen than the air ions escape. As the 

 velocity is increased the amount of electrification from the 

 air increases slowly, as nearly all of the ions are blown out, 

 while the amount from hydrogen increases rapidly as the 

 velocity increases. 



In a previous paper (loc. cit.) it was shown that hydrogen 

 was saturated for a much lower value of the E.M.F. than 



