Ionization of Hydrogen by X-Rays. 651 



ionization chamber B was also used. It was situated so as 

 to receive some of the rays from the radiator, while its 

 electrode was connected by shielded wires to an ordinary 



Fig. 3. 



To Electroscope 



To Pressure Gauge. 



\y/ To Hydrogen Supply. 



electroscope placed for convenience beside the scale of the 

 electrometer. The X-ray bulb was placed in a lead-lined 

 box, and the rays emerged in a vertical direction through an 

 aperture in the top of the box and fell on a radiator inclined 

 at about 45° to the vertical. Characteristic X-rays from this 

 radiator passed into the two ionization chambers. 



In order to be able to increase the pressure, another vessel 

 was connected to the ionization chamber, and at the start 

 the two were filled with hydrogen from the generating 

 apparatus. After being filled the chamber was exhausted 

 by means of an air-pump, this process being repeated several 



