﻿Alpha 
  Rays 
  by 
  Metals 
  and 
  Gases. 
  

  

  607 
  

  

  such 
  dimensions 
  that 
  the 
  cone 
  o£ 
  rays 
  emerging 
  from 
  it 
  fell 
  

   well 
  within 
  the 
  limits 
  of 
  the 
  ionization-chamber. 
  The 
  radium 
  

   bromide 
  was 
  set 
  at 
  such 
  a 
  distance 
  from 
  the 
  ionization- 
  

   chamber 
  that 
  a 
  part 
  of 
  the 
  top, 
  or 
  slightly 
  inclined 
  portion, 
  

   of 
  the 
  Bragg 
  ionization-curve 
  due 
  to 
  the 
  alpha-particles 
  from 
  

   radium 
  C 
  fell 
  within 
  the 
  chamber, 
  and 
  the 
  air-equivalents 
  of 
  

   the 
  various 
  metal 
  sheets 
  determined 
  at 
  various 
  points 
  in 
  the 
  

   path 
  of 
  the 
  rays 
  in 
  exactly 
  the 
  same 
  manner 
  as 
  that 
  used 
  in 
  

   the 
  first 
  experiments 
  *. 
  The 
  rays 
  of 
  shorter 
  range 
  than 
  those 
  

   of 
  radium 
  C 
  had 
  no 
  effect 
  upon 
  the 
  results 
  since 
  they 
  did 
  not 
  

   reach 
  the 
  ionization-chamber. 
  Beta 
  and 
  gamma 
  rays 
  are 
  

   also 
  given 
  off 
  by 
  the 
  radium 
  bromide, 
  but 
  the 
  ionization 
  pro- 
  

   duced 
  by 
  them 
  can 
  be 
  considered 
  as 
  a 
  constant 
  value 
  over 
  the 
  

   part 
  of 
  the 
  path 
  used, 
  and 
  consequently 
  the 
  effect 
  due 
  to 
  them 
  is 
  

   only 
  a 
  shifting 
  of 
  the 
  curves 
  to 
  the 
  right 
  parallel 
  to 
  themselves 
  

   which 
  would 
  have 
  no 
  effect 
  upon 
  the 
  results 
  under 
  consideration. 
  

   In 
  column 
  1, 
  Table 
  I., 
  are 
  given 
  the 
  different 
  metal 
  sheets 
  

   used 
  in 
  the 
  experiments. 
  Column 
  2 
  contains 
  the 
  thickness 
  in 
  

  

  Table 
  I. 
  

  

  I. 
  

  

  II. 
  

  

  III. 
  

  

  IV. 
  

  

  Metal 
  Sheets. 
  

  

  Thickness 
  in 
  cms. 
  

  

  Air-Equiralent 
  

   in 
  cms. 
  

  

  Eatio. 
  

  

  A 
  Au 
  

  

  1-27x10"^ 
  

  

  0-719 
  

  

  5-67x10^ 
  

  

  B 
  Au 
  

  

  1-74x10-* 
  

  

  0-980 
  

  

  5-63x10^ 
  

  

  C 
  Au 
  

  

  2-50 
  Xl0~* 
  

  

  1-375 
  

  

  5-50x10^ 
  

  

  D 
  Au 
  

  

  3-50x10-^ 
  

   3-86x10"^ 
  

   7-99x10-* 
  

  

  1-900 
  

   1-011 
  

  

  1-995 
  

  

  5-42x10-^ 
  

   2-61x103 
  

   2-48x103 
  

  

  A 
  Sn 
  

  

  B 
  Sn 
  

  

  A 
  Pb 
  

  

  2-84x10-* 
  

  

  1-104 
  

  

  3-88x103 
  

  

  B 
  Pb 
  

  

  4-lixlO-* 
  

   6-95x10-* 
  

   3-30x10"* 
  

  

  1-396 
  

   2-325 
  

  

  0-597 
  

  

  3-40x10=^ 
  

   3-34x103 
  

   1 
  -79x103 
  

  

  C 
  Pb 
  

  

  A 
  Al 
  

  

  B 
  Al 
  

  

  6-77x10-* 
  

  

  1-209 
  

  

  1-79x10'^ 
  

  

  C 
  Al 
  

  

  10-40x10-* 
  

  

  1-803 
  

  

  1-73x10'^ 
  

  

  D 
  Al 
  

  

  16-luxlO-* 
  

  

  2-072 
  

  

  1-66x10"'^ 
  

  

  Hydrogen 
  Sheets, 
  

  

  

  

  

  A 
  hydrogen 
  

  

  1-07 
  

  

  0-231 
  

  

  2-15x10""^ 
  

  

  B 
  hydrogen 
  

  

  1-93 
  

  

  0-428 
  

  

  2-21x10-^ 
  

  

  C 
  hydrogen 
  

  

  3-23 
  

  

  0-762 
  

  

  2-36x10-1 
  

  

  Loc. 
  cit. 
  pp. 
  173-175. 
  

  

  