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.XLVII. Experiments with Electron Currents in Different 

 Gases. (1) Mercury Vapour. By 0. W. Richardson, 

 F.R.S.* Wheat stone Professor of Physics, University of 

 London — King s College, and Charles B. Bazzoni, Ph.D.. 

 Instructor in Physics, University of Pennsylvania *. 



IN these experiments electron currents from an incan- 

 descent tungsten filament AB (fig. 1) flowed under 

 various potential differences to a cold anode of nickel 

 wire about 1*5 mm. in diameter. The filament AB was 

 about 1*5 cm. in length and *08 mm. in diameter. The 

 current across the gap A B to C has been measured under 

 various conditions. At the same time the nickel electrode E 



Fig-. 1. 



at the centre of the bulb H, which is covered on the inside 

 with a conducting layer of platinum, enabled the photo- 

 electric effect of the radiation from the discharge to be 

 examined. The connecting tube contained the tubular sheath 

 F and the central wire Gr. An electric field was applied 

 between F and G to stop the diffusion of ions from AB C to 

 the bulb E H. The apparatus shown in the figure was made 

 of transparent quartz, and could be maintained at various 

 temperatures by means of a specially constructed electric 



* Communicated bv the Authors. 



