C. Bar us — Thomson's Constant. 327 



The amount of exhaustion was equivalent to the volume 

 ratio v 1 /v=l'2d. Thus the number of ions in the fog chamber 

 at atmospheric pressure was ^=611,000 per cubic centimeter 

 for the uncharged core and n — 106,000 for the charged core. 

 Hence JV 2 -n 2 is about 362 XlO 9 . 



The value of &=l'lxl0 6 is taken from Prof. Kutherford's 

 book. The source of light for the corona is part of a 

 Welsbach mantle, as usual, and the old constants of coronas 

 were used, since it is a part of the purpose of this paper to 

 test those constants. The volume of the fog chamber was 

 estimated at 51,000 cu cm . In the first experiments, the effect 

 of the gamma rays penetrating into the air on the outside of 

 the fog chamber was neglected and the data on using different 

 condensers were as follows, all data being given in electrostatic 

 units. C denotes the capacity of the system, V the drop of 

 potential per second, i the corrected current passing through 

 the condenser fog chamber. 



c 



Fxio 8 



^xio a 



eXIO 



03 



10 



103 



fi'l 



47 



21 



101 



5-0 



47 



19 



92 



4-5 



17 



40 



70 



3'4 



the last observation being made without an auxiliary con- 

 denser. The current i was quite constant throughout the 

 voltage interval (near 250 volts) of observation. Hence the 

 effect of gamma ray penetration has seriously increased the 

 leakage, and e therefore appears too large, except in the last 

 observation, where i is probably no longer measureable. 



6. Further data. — In the following experiments the effect 

 of the external gamma rays was eliminated as specified in § 2. 

 The conduction current was usually quite negligible. The 

 nucleations observed in the exhausted fog chamber were n — 

 82,000 and iV Tl = 506,000, when the core was charged and un- 

 charged, respectively. The exhaustion was again equivalent 

 to a volume increase of vjv— 1*29. Hence in the fog chamber 

 full of air the respective nucleations are ^=653,000 and n— 

 106,000, whence JP-?i 2 =415Xl0 9 . 



The electrical measurements, if all data are given in electro- 

 static units, may be summarized as follows : 







Fxio 3 



^xio 2 



eXlO 10 



03 



7-5 



77 



3-3 



47 



17-2 



81 



3'5 



37 



19*6 



72 



3-1 



17 



33- 



58 



2-5 



