﻿232 
  

  

  Prof. 
  A. 
  S. 
  Eve 
  on 
  the 
  Secondary 
  y 
  Rayi 
  

  

  Fiff. 
  4. 
  

  

  20 
  

   18 
  

   16 
  

   14 
  

  

  r 
  

  

  

  

  ' 
  

  

  

  1 
  

  

  

  

  I 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  8 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  Ra 
  Bn 
  in 
  Steel 
  

  

  

  6 
  

  

  1 
  

  

  

  

  

  

  

  N 
  

  

  

  

  Lead 
  Screens 
  

  

  

  4 
  

  

  \> 
  

  

  

  

  

  

  ^ 
  

  

  \ 
  

  

  : 
  

  

  

  

  

  

  Z 
  

  

  I 
  

  

  ^ 
  

  

  ^^^ 
  

  

  

  

  

  

  V 
  

  

  — 
  — 
  - 
  — 
  

  

  ^^H 
  

  

  Uad 
  

  

  _____| 
  

  

  : 
  

  

  

  

  From 
  these 
  results 
  and 
  diagrams 
  the 
  following 
  deductions 
  

   may 
  be 
  made 
  : 
  — 
  

  

  1. 
  It 
  is 
  noteworthy 
  that 
  the 
  radium 
  in 
  2*2 
  cms. 
  of 
  nickel- 
  

   steel 
  gives 
  an 
  effect 
  about 
  1*5 
  times 
  as 
  great 
  as 
  when 
  the 
  

   radium 
  is 
  in 
  1 
  cm. 
  of 
  lead. 
  From 
  the 
  relative 
  densities 
  we 
  

   should 
  expect 
  2'2 
  cms. 
  of 
  steel 
  to 
  be 
  equivalent 
  to 
  1*5 
  cms. 
  of 
  

   lead 
  and, 
  therefore, 
  the 
  radium 
  in 
  the 
  steel 
  cylinder 
  should 
  

   give, 
  by 
  the 
  density 
  law, 
  two-thirds 
  the 
  effect 
  of 
  the 
  radium 
  in 
  

   the 
  lead. 
  It 
  actually 
  gives 
  one-and-a-half 
  times 
  as 
  much. 
  

   This 
  remarkable 
  result 
  was 
  confirmed 
  by 
  direct 
  reading 
  of 
  

   the 
  primary 
  7 
  rays 
  using 
  different 
  electroscopes. 
  Thus 
  the 
  

   primary 
  7 
  rays 
  traverse 
  steel 
  much 
  more 
  readily 
  than 
  lead, 
  

   but 
  the 
  rays 
  passing 
  through 
  iron 
  are 
  subsequently 
  absorbed 
  

   more 
  readily 
  by 
  lead 
  than 
  it' 
  the 
  radium 
  were 
  in 
  lead. 
  The 
  

   values 
  for 
  X, 
  the 
  coefficient 
  o£ 
  absorption 
  by 
  lead, 
  between 
  

   2 
  and 
  4 
  cms. 
  were 
  ;is 
  follows 
  : 
  — 
  

  

  Radium 
  in 
  lead 
  ( 
  1 
  cm. 
  ) 
  \= 
  *47 
  

   „ 
  Bteel 
  (2-2 
  cms.) 
  A 
  = 
  1 
  - 
  1 
  

  

  ,, 
  „ 
  (4 
  cms.) 
  \ 
  = 
  '75 
  

  

  primary 
  

  

  7 
  rays. 
  

  

  ~1. 
  The 
  secondary 
  rays 
  of 
  the 
  7 
  type 
  Erom 
  lead 
  are 
  Eeeble 
  

   compared 
  with 
  those 
  from 
  iron 
  or 
  brick. 
  This 
  i- 
  true 
  whether 
  

  

  