232 Mr. E. Jacot on a Relation between Ionization by 

 than this expression that are made per cm. by a corpuscle-. 



mrd 2 



moving through the gas is 



or 



mre* 



(*-•) 



This is a maximum when T = 2W. 



In the case of cathode particles T is large compared with 

 W and the expression becomes 



mre* 



W'jr 



Hence the number of ions produced per cm. by cathode 



particles varies as ^ ; that is, inversely as their kinetic 

 energy. 



The results of the work described in Part II. above are in 

 agreement with the theory. 



(2) Calculation of the proportion of nitrogen, ionized by 

 rays of known velocity, that enters into combination with 

 phosphorus. 



The following will serve as an example : — 



At the beginning of an experiment, 



(1) The ionization-chamber (volume V 2 = 90*12 c.c.) 



contained nitrogen under a pressure '041 mm. 



(2) The volume V 3 = 343*78 c.c. was thoroughly ex- 



hausted, the pressure as recorded by the gauge 

 being of the order of '0001 mm. 



After the passage through V 2 of rays of velocity 3*7 x 10 9 

 cm. per sec, the gas in V 2 was shared between V 2 and V 3 

 and the resultant pressure recorded : *0085 mm. nitrogen, 

 then ("active" and "inactive"), occupied a total volume 

 V 2 -j-V 3 = 433*90 c.c. under a pressure '0085 mm. Of this, a 

 volume 433*90 c.c. under *0035 mm. press, was " active " ; 

 and a volume 433*90 c.c. under *0050 mm. press, was 

 "inactive." A ratio R = *41 of the total gas was therefore 

 "active." 



The values of R for the series of experiments are collected 

 in column 7 of Table I. 



^Numerical estimates of the number of ions in any given 

 mass of " active " nitrogen after admission to the phosphorus 



