110 



The tubes were first filled with an almost saturated solution of Cu 

 So 4 . On working for two days with this electrolyte trying many different 

 adjustments it was found that the back or electrolytic E. M. F. was so 

 variable that no reliable results could be secured. The only thing deter- 

 mined positively was that lengthening the distance between the disks 

 in I caused a deflection E, and lengthening that in II produced a deflec- 

 tion W. 



On filling the tubes with pure distilled water the results were some- 

 what more definite. With the disks 1* cm. apart the following data 



Figure 1. 



Dimensions of essential parts of apparatus of Figure 1. 



(1) Glass tubes, I and II. 



Length of each, 10 cm. 



Internal diameter of each, 17 mm. 



(2) Copper discs, dl, (12. d3, and dl. 



Diameter of each, l(i mm. 

 Thickness of each, 1 nun. 



