550 



Mr. A. Schuster. 



Answer: — If v is taken as 17xl0 4 , and e=3/cXl0 -23 , the 

 distance is 2/cxJ0~ 8 , which is larger, though not considerably so, 

 than the molecular distance. We conclude that two particles 

 charged with the same kind of electricity will, in general, not 

 approach each other sufficiently near to bring other than electrical 

 forces into play. 



Question III : — At what distance is the force between two equally 

 charged atoms equal to the force in a field in which the fall of 

 potential is 1 volt per centimeter ? 



Answer : — r = */3k . 10~ 5 . If the fall is 1 volt per mm., the 

 distance would be three times as great, or about 5 X 10~ 5 . 



Question IV: — What is the proportion of ions amongst the 

 molecules in the positive part of the discharge ? 



Answer: — I assume, as a first approximation, the velocity of 

 diffusion to be that of the mean velocity of the gas in the normal 

 state. (One measurement of the magnetic deflection in the glow 

 shows that the velocity of diffusion cannot be much greater, and the 

 answer to Question II shows that it cannot be much smaller.) If 

 S is the cross-section of the tube, C the current, and n the number 

 of ions, we have 



nSev — ; Km = />, 



where "N is the number of undecomposed molecules, and p the density 

 of the gas. Combining the two equations : 



n mC 

 N ~ S.e.v.p' 



In a typical example, p was 5 X 10~ 7 ; = 3 X 10~ 4 ; S = 2 ; and as; 



e -= 10 4 , we find 



m 



n[8 = i X 10~ 6 , 



a small fraction, which is suggestively near the fraction obtained for 

 the proportion of positive ions in close contact with the kathode 

 the two results being observed from altogether different quantities. 



Question V : — What is the average distance between the ions in 

 the positive part of the discharge ? 



Answer : — With the same data as in Question IV, I find for the- 

 average distance approximately 10 -3 , or y 1 ^ mm. 



Probable Explanation of the Fall of Potential observed at the 

 Kathode. 



In carrying out the investigation of which the experiments- 

 described in this paper form a part, I have always attached most 



