548 



Sir E. Rutherford on Collision of 



in the region of short ranges for which some of the values are 

 calculated. It is seen that while the number of H atoms for 



Fij 



2-4- 



2-0 



1-6 



\ 





























1 







A. Rang 

 B " 



C » 



e of <x rays 7 cm 

 5 » 



„ 3 „ 



;. 



n /Q 















































\° 



\# ^ 









10 

 F?3ngt 



14 18 22 



ifH atoms in cms. of air 



26 



30 



short ranges increases rapidly with the reduction of range of 

 the « particle, the three curves show approximately the same 

 ordinates for 6*5 cm. range of the H atoms. 



§ 8. Absorption ofH atoms. 



The source of a rays was a brass disk coated with radium 

 only in the central part, in order to reduce the area emitting 

 a. rays. The initial 7-ray activity of the disk was equivalent 

 to about 10 mg. Ra. The zinc sulphide screen was mounted 

 parallel to the disk in the apparatus shown in fig. 1 at 3*3 cm. 

 distance from the source. An opening in the end of the box 

 was covered with a heated silver plate, whose absorption 

 for a particles was equivalent to 5*8 cm. of air, and the 

 whole apparatus was filled by exhaustion with dry hydrogen, 

 at atmospheric pressure. Suitable absorbing screens of 



