242 Mr. E. Kutherford on the Electrification 



The method of separation used was to direct a rapid current 

 of air or other gas along the surface of the charged electrode 

 of a vessel exposed to the Eontgen rays ; a large metal 

 cylinder was taken, either of thin metal to allow the rays to 

 readily pass through the side, or a piece was cut out and a 

 sheet of very thin metal substituted to serve the same pur- 

 pose. 



Fig. 1. 



TO Urtttery 



A (fig. 1) was the metal cylinder, B C a glass tube fixed 

 centrally inside the cylinder. The wire D E was fixed in the 

 glass tube B C and supported by thin metal spikes in the 

 centre of the tube. Several inches of wire, B D, projected 

 from the glass tube. A current of gas was sent from a pair 

 of bellows or a gas reservoir along the tube C B, and then 

 along a metal tube . into an insulated conductor connected 

 with one pair of quadrants of an electrometer, the other pair 

 being connected to earth. The wire D E was connected to 

 one pole of a battery of small lead cells, the other pole being 

 to earth. The outside of the cylinder was connected to earth, 

 and the bulb and Ruhmkorff coil were placed inside a metal 

 tank, so as to completely screen the outside apparatus from 

 electrostatic disturbances. A hole was cut in the tank, and 

 the bulb arranged so as to allow the rays to fall on the part 

 B D of the charged wire. 



When the bulb was not working, however rapid a current 

 of air was sent along the charged electrode, no electrification 

 was obtained in the inductor, but the moment the rays were 

 turned on the inductor became charged opposite in sign to the 

 charged wire. The deflexion of the electrometer continuously 

 inc eased as long as the rays and blast of air were acting. 



The inductor was generally placed some feet from the 

 generating vessel A, the air passing to the inductor through 

 a metal tube of 3 cm. diameter. Since the electrification of 



