344 



Prof. W. H. Bragg on the Ionization of 



that 111 = 289. The pressure has altered about 1 cm. during 

 the determination of the curve, but was found to be 23*35 at 

 the moment when the corner (R, I) was passed. The tempe- 

 rature at the same time was 29°. Now the stopping-power of 



Fig. 5. 



9 cm 











1* 











8cm 1 





233.5-rnm 



29*C. 



air a% 





1 o 



""*— -^ 



R = 7Vi- 

 1 = 373 

 Rl = 289 







3 



4 



5 



6 



7 



0S 2 is 2*20, and the stopping-power of the mixture is (com- 

 paring with the previous experiment) 



495 



774 



75:l_ 



233-5 



= 2-06. 



Hence 



If x be the percentage of gas, we must have 



<rx2-2 + l-<r=2-06, .-. .,;=88*5. 



The vapour is then cleared out of the apparatus, and dry air 

 admitted. The value of RI for air is again determined, as 

 shown in fig. 6, and found to be 214. 



In the second experiment the proportion of gas to air, by 

 pressure, is as 88'5 to 11*5; but, according to the energy spent 

 by the a particle, as 88*5 to 11*5/2*2, i. e., as 94*5 to 5'5. Hence 



