340 



Prof. W. H. Bragg on the Ionization of 



The tube A goes to the manometer, B to a bulb used in the 

 determinations o£ stoppingvpower, and to a bulb which 

 contains the liquid whose vapour is being treated. 



The following tables contain the results of the determi- 

 nation of the constant of specific ionization due to a. rays. 

 These have all been made recently, except when the contrary 

 is stated. I have rejected a large number of earlier mea- 

 surements. In the case of each experiment with a gas, the 

 value of RI for air w r as found immediately before and imme- 

 diately afterwards. It varies somewhat from day to day, 

 and generally increases during any long series of experiments, 

 since the warmth and dryness are conducive to the better 

 retention of the emanation. The radium plate is not quite in 

 so good a condition as it used to be, being covered with a very 

 thin film of dirt and grease (mainly from the taps). This 

 could, no doubt, be removed by a red heat ; but I am 

 unwilling to handle the radium film so roughly just now. 

 The presence of the film slightly lowers the ranges, about "5 

 to 1 mm. in air; and rather blurs the corners of the ionization 

 curves. 









Percent. 



Percent. 











Volts 



Pressure 



Tempe- 



of Gas by 



of Gas by 



EI. 



EI 



EI 





per cm. 



in cm. 

 Pentane. 



rature. 



Pressure. 



Energy. 





(corrd.) 



(air). 



Eatio 



1670 



25 



44-5 



83-5 



95 



262 



265 



198 



1-34 



., 



32-7 



43 



79-5 



93-5 



261 



265 



198 



1-34 



} , 



23-75 



35 



91-5 



97-5 



26! 



263 



197 



1-33 



., 



29 4 



37-8 



88-5 



96-5 



265 



267 



197 



1-35 





38-5 



40 



81 



94 



271 



275 



200 



1-37 





39-6 



37-5 



91 



97 



277 



279 



208 



134 



1000 



32-6 



39 



88-5 



96-5 



281 



284 



208-5 



136 



» 



25-6 



40 



88-5 



96-5 



282 



285 



209 



Mean 



1-36 



1-35 





Carbon Bisulphide. 















1670 



25-8 



40 



91 



96 



282 



285 



209-5 



1-36 



1000 



23-35 



29 



88-5 



94-5 



289 



294 



213 



1-38 



" 



301 



40 



91 



96 



284 



287 



209-6 



Mean 



1-37 

 1-37 





Ether (C 4 



H 10 O). 















1000 



24-2 



29-7 



82-5 



94-5 



274 



277 



214 



1-295 



1670 



247 



30 



86-5 



95-5 



277 



280 



214 



1-31 





26-2 



49-5 



87 



96 



270 



273 



207 

 Mean 



1-32 

 1-31 





Chloroform. 















1670 



26-1 



50-5 



86 



95 



262 



265 



207 



1-28 



„ 



23-5 



50 



86 



95 



262 



265 



207 



1-28 





27-4 



54 



83 



94 



260 



264 



202 



Mean 



131 



1-29 



