Various Gases by the a. Particles of Radium, 3^5 

 the true value of III is found from the equation 

 •945RI+-055X 213=289; 

 whence PI = 291. 



Hence specific ionization of CS 2 = 294/2 13 =1*38. 

 The results of this particular experiment are recorded in 

 the second line of the results for carbon bisulphide in § 2. 







Fig. 6. 







|6cm 7 











/ * 











*/ 











7 





air 



751 rnm 

 30°C 



1 =A3'3 





$cin/ 







R! = 2ll f 





1 



5 



6 



7 



r j 



It seems probable that the determination of the ionization 

 in various cases due to the a rays may be of considerable 

 importance, and I therefore attach a drawing of the apparatus 

 which I have used (Plate IX.) in the hope that it may save 

 the time of any other workers in this direction. 



In the figure, P is one of the three glass pillars which 

 support the high potential plate. I have also used a glass 

 plate, as shown by the dotted surface, to insulate the upper 

 plate of the ionization-chamber. Sulphur and ebonite do not 

 stand the heat. The upper gauze, </g, is the lower wall of 

 the chamber, (J (J is the lower gauze and is earthed ; it is sup- 

 ported by three brass pillars, only one of which is shown. The 

 vertical tubes are shown at TT, and the radium plate at P R. 

 The semaphore, ss, is made of thin sheet-copper, and can be 

 turned round so as to uncover the radium. It may be worth 

 while mentioning that I have found it better to keep the 

 plate, QQ, " out of sight " of any insulating material con- 

 nected with the high- potential plate; and if this is not done 

 then the creep of electricity over the insulators, which is apt 

 to occur when the potential is changed, exerts a troublesome 

 electrostatic effect. DEFGis the outline of the electric oven. 



