354 Charge of Electricity carried by a Gaseous Ion. 



The results of the determinations of ne, where n is the 

 number of ions per c.c, and e the charge in electrostatic 

 measure on an ion. are given in the following table. I) is 

 the deflexion of the electrometer in scale-divisions for the 

 potential-difference o£ 1 volt, C is the capacity of the electro- 

 meter and its connexions, 8 f the mean of the positive and 

 negative deflexions in one minute of the electrometer when 

 there was a potential- difference of ^ of a volt between the 

 plates of the condenser, the gas between the plates being- 

 exposed to the radiation from the radium A at a distance of 

 10 cms., $ 2 th e same quantity when the gas was exposed to 

 the radiation from B at a distance of 15 cms. The values of 

 ne are deduced as follows : if A is the area of the plate 

 attached to the electrometer, u the mean velocity of the posi- 

 tive and negative ions under a potential-gradient of a volt 

 per cm., the quantity of electricity given to this plate in unit 

 time under J of a volt per cm. is equal to %neuA, this pro- 

 duces a potential-difference of l nea A/C in electrostatic 

 measure between the plates ; the potential-difference in volts 

 is, however, V60D, hence we have 



1 neuA 



6013 X 300" 



From Zeleny's experiments u for moist air is 1*4 cm./sec, 

 A = 19-1; we have thus the data for determining ne : — 



" 



c. 



*i- 



l 2 . 



ne 

 for radium A. 



ne 

 for radium B. 



7400 



6550 



7600 



! 8800 



483 

 640 

 900 

 930 



63 

 30 

 25-5 



28 



170 



71-5 



78 



252x10-6 

 207x10-6 

 19 xlO-6 

 18-5x10-6 



68x10-6 



53x10-6 

 52x10-6 









Mean... 20-8x10-6 



576x10-6 



Thus, since for radium A ne — 20*8 x 10 -6 and n— 6*25 X 10 1 , 

 the value of e = 3'3 x 10~ 10 : 



For radium B 7^ = 57*6 x 10~ 6 and ?* = 16*75 x 10 4 , thus 

 e = 3-5xl0- 10 . 



The mean of the^e values gives 3*4 x 10 -10 as the charge 

 in electrostatic units of the gaseous ion. This is only about 

 half the value 6*5 x 10 -10 I found in the earlier experiments. 

 The difference is, as I have already explained, due to the ex- 

 pansions in the earlier experiments practically catching only 

 the negative ions ; this made the calculated value of n little 



