by Matter of the Particles emitted by Radium. Ill 



For this purpose, an aperture was cut in an ordinary /3-ray 

 electroscope and closed by a thin aluminium filter just thick 

 enough to absorb the a rays. The thin-walled glass tube was 

 then placed just outside the electroscope, as close up to the 

 aluminium as possible, and various thicknesses o£ glass tubing 

 interposed between the emanation and the electroscope by 

 passing glass tubes over the tube containing the emanation. 

 The results obtained were then compared with those given by 

 Schmidt for aluminium. The results are shown graphically 

 in fig. 2, from which it will be seen that the absorption-curves 

 for glass and aluminium are substantially the same. The curve 









Fig. 2. 













]0O 



SO 































60 

 40 































\ 

















10 



\ 

















+ 



























^ 



. o 











Y 



V 



B 



1 



i 1 



6 



1 



O 



MilliTnetzis oj Gl 



+ By LoT\i2.a.tion. 

 O By Cha-rqE 



aSS 



is drawn from the values of the ionization obtained by Schmidt 

 when different thicknesses of aluminium were interposed 

 between the radium B and C and the electroscope. The 

 points marked ( -{- ) indicate the value of the ionization ob- 

 tained in the experiment with glass when the thickness of 

 glass traversed by the /3 rays was increased by superposing 

 successive olass tubes over the tube containing the emanation. 



Phil. Mag. S. 6. Vol. 17. No. 97. Jan. 1909. 



N 



