﻿Radium 
  Emanation 
  in 
  the 
  Atmosphere. 
  

  

  595 
  

  

  plotted. 
  It 
  will 
  be 
  noted 
  that 
  for 
  all 
  times 
  the 
  ordinates 
  

   of 
  the 
  curves 
  for 
  the 
  same 
  value 
  of 
  t 
  add 
  up 
  to 
  a 
  constant 
  

   amount 
  {i.e. 
  I 
  t 
  + 
  I/ 
  = 
  T 
  ). 
  

  

  Fiff. 
  2. 
  

  

  50 
  

  

  I 
  

  

  k 
  

  

  1 
  

  

  30 
  

  

  20 
  

  

  10 
  

  

  

  

  \A 
  

  

  

  

  

  

  

  

  

  AB 
  -DECAY 
  CURVE. 
  

  

  CD 
  - 
  PRODUCT/ON 
  CURVE. 
  

  

  

  

  

  

  

  

  

  

  2> 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  B 
  

  

  c/ 
  

  

  

  

  

  

  

  

  

  

  2 
  3 
  4- 
  

  

  T/P7E 
  -/N 
  DAYS 
  

  

  If, 
  for 
  instance, 
  the 
  emanation 
  is 
  measured 
  when 
  it 
  is 
  

   one 
  day 
  old, 
  its 
  measured 
  amount 
  must 
  be 
  multiplied 
  by 
  

  

  °- 
  or 
  1*22 
  in 
  order 
  to 
  find 
  what 
  the 
  amount 
  would 
  have 
  been 
  

  

  41 
  

  

  if 
  it 
  had 
  been 
  measured 
  when 
  collected. 
  The 
  factors 
  for 
  2 
  

  

  and 
  3 
  days 
  are 
  1*47 
  and 
  1'IS 
  respectively. 
  

  

  Again, 
  if 
  a 
  radium 
  compound 
  is 
  cleared 
  of 
  all 
  emanation 
  

   and 
  then 
  left 
  to 
  itself 
  for 
  two 
  days, 
  the 
  amount 
  of 
  emanation 
  

  

  accumulated 
  is 
  only 
  -^ 
  of 
  the 
  amount 
  of 
  emanation 
  that 
  would 
  

  

  be 
  generated 
  and 
  in 
  existence 
  were 
  the 
  radium 
  left 
  until 
  it 
  was 
  

   in 
  radioactive 
  equilibrium 
  with 
  its 
  emanation. 
  

  

  The 
  " 
  production" 
  curve 
  C 
  D, 
  drawn 
  to 
  the 
  scale 
  of 
  fig. 
  2, 
  

   will 
  not 
  give 
  us 
  accurate 
  values 
  of 
  1/ 
  for 
  small 
  values 
  of 
  t. 
  It 
  

   must 
  be°expanded 
  in 
  its 
  initial 
  stages. 
  The 
  equation 
  of 
  the 
  

   production 
  curve 
  may 
  be 
  written 
  as 
  

  

  V 
  

  

  =l-*- 
  w 
  , 
  

  

  2R2 
  

  

  