On the Passage of Electricity through Gases. 393 



however, the current of air was flowing there was a consider- 

 able leak, showing that the air after exposure to the rays 

 retained its conducting properties for the time (about \ second) 

 it took to pass from the aluminium vessel to the charged 

 electrode. 



We tried whether the conductivity of the gas would be 

 destroyed by heating the gas during its passage from the 

 place where it was exposed to the rays to the place where its 

 conductivity was tested. To do this we inserted a piece of por- 

 celain tubing which was raised to a white heat ; the gas after 

 coming through this tube was so hot that it could hardly be 

 borne by the hand ; the conductivity, however, did not seem 

 to be at all impaired. If, however, the gas is made to bubble 

 through water every trace of conductivity seems to disappear. 

 The gas also lost its conductivity when forced through a plug 

 of glass wool, though the rate of flow was kept the same as 

 in an experiment which gave a rapid leak; if the same plug 

 was inserted in the system of tubes before the gas reached 

 the vessel where it was exposed to the Rontgen rays, in this 

 case the conductivity was not diminished. This experiment 

 seems to show that the structure in virtue of which the gas 

 conducts is of such a coarse character that it is not able to 

 survive the passage through the fine pores in a plug of glass 

 wool. A diaphragm of fine wire gauze or muslin does not 

 seem to affect the conductivity. 



A very suggestive result is the effect of passing a current 

 of electricity through the gas on its way from the aluminium 

 vessel where it is exposed to the Rontgen rays to the place 

 where its conductivity is examined. We tested this by inserting 

 a metal tube in the circuit, along the axis of which an insu- 

 lated wire was fixed connected with one terminal of a battery 

 of small storage-cells, the other terminal of this battery was 

 connected with the metal tube ; thus as the gas passed through 

 the tube a current of electricity was sent through it. The 

 passage of a current from a few cells was sufficient to greatly 

 diminish the conductivity of the gas passing through the 

 tube, and by increasing the number of cells the conductivity 

 of the gas could be entirely destroyed. Thus the peculiar 

 state into which a gas is thrown by the Rontgen rays is 

 destroyed when a current of electricity passes through it. It 

 is the current which destroys this state, not the electric field ; 

 for if the central wire is enclosed in a glass tube so as to stop 

 the current but maintain the electric field, the gas passes 

 through with its conductivity unimpaired. The current pro- 

 duces the same effect on the gas as it would produce on a very 

 weak solution of an electrolyte. For imagine such a solution 



