Two Tons produced in Gases hy 11 out gen Radiation. L39 



pressure is established in the box RS, and a narrow stream 

 goes between the two openings C and D, which disturbs but 

 little the surrounding air. In this way it is possible, by 

 moving the slits relative to the plates, to carry out the air 

 from any particular region between the two plates and to 

 measure its charge. 



As the plates are symmetrically placed and symmetrically 

 charged relative to the box, which is to earth, the space 

 between their central portions is in a fairly uniform field 

 when the plates are close together. 



The source of rays is placed so that the radiation passes 

 through the side of the box RS in a direction perpendicular 

 to the plane of the figure, and impinges uniformly upon the 

 air between the plates. 



In taking readings the blast and raj^s were turned on for a 

 short time to establish a steady state, and then the electro- 

 meter quadrants, with the connected glass-wool, were dis- 

 connected from earth : and after 30 seconds the rays were 

 cut off and the electrometer deflexion read. 



The following Table gives the deflexions obtained in a 

 sample case where the plates were 5 centim. apart, and were 

 charged to 4- 705 volts and —70*5 volts: — 



Table IV. 



Distance of centre of slits 

 from negative plate. 



Deflexion. 



centim. 

 •5 



+ 168 



1-0 



4- 74 



1-5 



-f 42 



20 



4- 22 



2-5 



+ 1 



30 



- 16 



35 



- 40 



40 



- 65 



45 



-138 



The results are shown graphically in fig. 8, where the 

 abscissae represent distances of the slits from the negative 

 plate, and the ordinates represent the deflexions obtained, 

 which are proportional to the densities of the free electrifica- 

 tion existing at the various points between the two plates. 



