﻿Wellisch 
  and 
  Woodrow 
  — 
  Columnar 
  Ionization. 
  227 
  

  

  Corresponding 
  values 
  of 
  y 
  and 
  a 
  were 
  chosen 
  at 
  various 
  points 
  

   along 
  the 
  curve 
  A, 
  fig. 
  5 
  ; 
  from 
  the 
  value 
  of 
  y 
  that 
  of 
  x 
  was 
  

   obtained 
  by 
  computation, 
  using 
  equation 
  (2), 
  and 
  then 
  making 
  

  

  = 
  — 
  -, 
  Q 
  was 
  determined. 
  The 
  values 
  

  

  use 
  of 
  the 
  relation 
  

  

  of 
  Q 
  obtained 
  by 
  choosing 
  different 
  values 
  for 
  y 
  should 
  be 
  

   constant. 
  A 
  set 
  of 
  values 
  determined 
  in 
  this 
  way 
  is 
  given 
  in 
  

   Table 
  Till. 
  The 
  values 
  of 
  Q 
  are 
  given 
  in 
  arbitrary 
  units. 
  

  

  Table 
  VIII. 
  

   Different 
  Position 
  of 
  the 
  Axis. 
  

  

  

  •73. 
  

  

  •74. 
  

  

  • 
  i 
  

  

  5. 
  

  

  y 
  

  

  X 
  

  

  Volts/cm. 
  

  

  Qo. 
  

  

  X. 
  

  

  Qo. 
  

  

  X. 
  

  

  Qo. 
  

  

  0-46 
  

  

  75 
  

  

  66-3 
  

  

  90 
  

  

  79-6 
  

  

  105 
  

  

  92-8 
  

  

  0-5 
  5 
  

  

  140 
  

  

  82-5 
  

  

  150 
  

  

  88-3 
  

  

  160 
  

  

  94-3 
  

  

  0-61 
  

  

  190 
  

  

  84-0 
  

  

  195 
  

  

  86-1 
  

  

  210 
  

  

  92*8 
  

  

  0-66 
  

  

  230 
  

  

  81-3 
  

  

  245 
  

  

  86-6 
  

  

  250 
  

  

  88-3 
  

  

  0-75 
  

  

  338 
  

  

  749 
  

  

  350 
  

  

  77-2 
  

  

  360 
  

  

  79*6 
  

  

  0-81 
  

  

  460 
  

  

  67*8 
  

  

  550 
  

  

  81-0 
  

  

  520 
  

  

  76*6 
  

  

  In 
  order 
  to 
  obtain 
  an 
  idea 
  of 
  the 
  sensibility 
  of 
  the 
  method, 
  two 
  

   other 
  straight 
  lines 
  parallel 
  to 
  D£ 
  and 
  close 
  to 
  it 
  were 
  chosen 
  

   as 
  axes. 
  The 
  values 
  of 
  Q 
  obtained 
  by 
  choosing 
  different 
  

   values 
  for 
  y 
  along 
  rhe 
  curve 
  A 
  when 
  the 
  axes 
  were 
  at 
  0*73, 
  

   0*74, 
  and 
  0*75 
  are 
  given 
  in 
  the 
  above 
  table. 
  It 
  will 
  be 
  seen 
  

   that 
  the 
  values 
  for 
  the 
  axis 
  at 
  0'74 
  are 
  more 
  nearly 
  constant 
  

   than 
  for 
  the 
  other 
  two 
  positions 
  of 
  this 
  axis. 
  With 
  the 
  axes 
  

   farther 
  away, 
  the 
  values 
  differ 
  much 
  more 
  ; 
  that 
  is, 
  the 
  values 
  

   of 
  Q 
  are 
  more 
  nearly 
  constant 
  even 
  for 
  the 
  large 
  values 
  of 
  y 
  

   when 
  the 
  axis 
  is 
  chosen 
  so 
  as 
  to 
  pass 
  through 
  the 
  point 
  where 
  

   the 
  curve 
  appears 
  to 
  intersect 
  the 
  axis 
  of 
  ordinates. 
  

  

  Taking 
  the 
  straight 
  line 
  DE 
  as 
  the 
  axis, 
  the 
  average 
  of 
  the 
  

   values 
  obtained 
  for 
  Q 
  is 
  82*3, 
  which 
  when 
  reduced 
  to 
  E. 
  S. 
  

   units 
  gives 
  Q 
  = 
  0*274. 
  Taylor* 
  has 
  determined 
  the 
  total 
  

   number 
  of 
  ions 
  produced 
  by 
  a 
  single 
  alpha 
  particle 
  from 
  

   polonium 
  in 
  air 
  at 
  a 
  pressure 
  of 
  one 
  atmosphere 
  : 
  his 
  calcula- 
  

   tions 
  give 
  this 
  number 
  to 
  be 
  164,000. 
  The 
  ratio 
  of 
  the 
  area 
  of 
  

   that 
  portion 
  of 
  the 
  'Bragg' 
  ionization 
  curve, 
  included 
  between 
  

   the 
  two 
  ordinates 
  corresponding 
  to 
  distances 
  2*4 
  cm 
  and 
  2*8 
  cm 
  

   from 
  the 
  polonium, 
  to 
  the 
  total 
  area 
  enclosed 
  by 
  the 
  curve 
  and 
  

   the 
  axes, 
  was 
  found 
  to 
  be 
  0-112. 
  Then 
  each 
  alpha 
  particle 
  will 
  

  

  * 
  Taylor, 
  Phil. 
  Mag. 
  (6), 
  yxiii, 
  p. 
  670, 
  1912. 
  

  

  