512 



Mr. H. A. Wilson on the Variation of th 



Fig. 7 shows the alternate rising and falling of the electric 

 intensity in and between the striae in the positive column. 



Fig. 7. — Discharge in Hydrogen. 

 Pressure 2'25 mms. Current 586 milliampere. 



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The variations in the electric intensity near the positive 

 electrode are very similar to those which occur between the 

 positive column and the negative electrode, although crowded 

 into a much smaller space. At each electrode there is a 

 sudden drop of potential followed by a region of very small 

 intensity. 



Prof. Thomson has shown (Joe. cit.) that where the ioni- 

 zation is in excess the intensity-curve must be concave 

 upwards, and concave downwards where the recombination is 

 in excess. From this we see that very close to the positive 



Fig. 8. — Discharge in Air. 

 Pressure 0'18 mm. Current 0*436 milliampere. 



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electrode there is very intense ionization going on, and also 

 in the negative glow and Faraday dark space ionization is in 

 excess. 



