70 



THE THEORY OF IONIZATION OF GASES 



pressure, as may be seen from the following experiments 

 with air. Instead of depending on the charge on the 

 positive ions to intensify the field near the negative 

 electrode, a gauze may be used near the negative electrode 

 and maintained at any required potential. 



Two electrodes, A and B, were set up, as shown in the 

 accompanying diagram, figure 12, in an air-tight glass 

 tube, and a grating of fine wire G was placed near the 

 negative electrode, and could be charged to any potential 



Figure 12. 



V intermediate between those of A and B by means of 

 a separate connection. The sparking potential between A 

 and B was then found to depend on the potential of the 

 grating. The following results 1 were obtained, in which 

 V represents the potential difference between the 

 grating and the negative electrode and Y the sparking 

 potential between A and B : 



Philosophical Magazine, June, 1906. 



