﻿'360 
  Messrs. 
  E. 
  Marsden 
  and 
  R. 
  H. 
  Wilson 
  on 
  some 
  

  

  from 
  the 
  slow 
  (3 
  rays 
  of 
  B, 
  which 
  are 
  intensely 
  ionizing. 
  

   With 
  stannous 
  chloride 
  present 
  as 
  impurity, 
  a 
  larger 
  amount 
  

   of 
  B 
  will 
  be 
  present 
  for 
  the 
  same 
  a-ray 
  activity 
  due 
  to 
  the 
  

   absorption 
  in 
  the 
  material. 
  

  

  0-6 
  0-8 
  

  

  7/ 
  ml 
  _ 
  Hours. 
  

  

  To 
  throw 
  further 
  light 
  on 
  the 
  possible 
  separate 
  existence 
  

   of 
  C 
  a 
  and 
  C|3, 
  experiments 
  were 
  also 
  made 
  with 
  j3 
  rays. 
  The 
  

   /3 
  rays 
  of 
  Cp 
  have 
  an 
  absorption 
  coefficient 
  in 
  aluminium 
  of 
  

   13*5 
  cm. 
  -1 
  and 
  those 
  of 
  D 
  21' 
  5 
  cm. 
  -1 
  Pure 
  was 
  deposited 
  

   on 
  a 
  nickel 
  plate 
  by 
  immersion 
  in 
  a 
  hot 
  dilute 
  hydrochloric 
  

   acid 
  solution 
  of 
  the 
  active 
  deposit. 
  The 
  rise 
  curves 
  by 
  

   ft 
  rays 
  due 
  to 
  the 
  growth 
  of 
  D 
  were 
  determined, 
  (1) 
  when 
  

   stannous 
  chloride 
  was 
  added 
  to 
  the 
  active 
  deposit 
  solution, 
  

   and 
  (2) 
  with 
  no 
  stannous 
  chloride. 
  No 
  difference 
  could 
  be 
  

   detected. 
  Further, 
  after 
  the 
  D 
  had 
  attained 
  equilibrium, 
  i. 
  e. 
  

   about 
  twenty 
  minutes, 
  the 
  ratio 
  of 
  the 
  /3-ray 
  activity 
  through 
  

   0*015 
  cm. 
  Al 
  and 
  0'12 
  cm. 
  Al 
  was 
  measured 
  in 
  each 
  case 
  

   and 
  found 
  to 
  be 
  the 
  same. 
  Owing 
  to 
  the 
  different 
  absorption 
  

   of 
  the 
  ft 
  rays, 
  this 
  ratio 
  would 
  depend 
  on 
  the 
  relative 
  amounts 
  

   of 
  D 
  and 
  Op 
  present, 
  and 
  the 
  result 
  thus 
  indicates 
  no 
  separa- 
  

   tion 
  of 
  Cp 
  from 
  the 
  parent 
  of 
  D, 
  i. 
  e. 
  a 
  on 
  the 
  above 
  scheme. 
  

  

  