﻿Radium 
  Emanation 
  in 
  the 
  Atmosphere. 
  

  

  613 
  

  

  Comparison 
  of 
  the 
  Efficiencies 
  of 
  the 
  Charcoal 
  and 
  

   Condensation 
  Methods. 
  

  

  It 
  is 
  quite 
  possible 
  that 
  in 
  neither 
  method 
  is 
  the 
  whole 
  of 
  

   the 
  emanation 
  taken 
  out 
  of 
  the 
  air 
  ; 
  it 
  is, 
  however, 
  hoped 
  with 
  

   each 
  method 
  the 
  same 
  fraction 
  of 
  the 
  emanation 
  in 
  the 
  air 
  

   and 
  the 
  emanation 
  from 
  the 
  solution 
  will 
  be 
  absorbed 
  so 
  that 
  

   the 
  comparisons 
  made 
  are 
  correct. 
  To 
  test 
  the 
  relative 
  values 
  

   of 
  these 
  fractions 
  I 
  did 
  two 
  experiments 
  in 
  which 
  the 
  charcoal 
  

   tube 
  and 
  the 
  condenser 
  were 
  put 
  in 
  parallel 
  thus 
  : 
  — 
  

  

  0: 
  

  

  -H3aCl 
  2 
  - 
  

  

  ->CaCU- 
  

  

  ->Ckarcoal 
  tube 
  A 
  ■ 
  

  

  ->Condenser 
  

  

  — 
  >Gauge 
  A 
  

   ■> 
  Gauge 
  C- 
  

  

  ie 
  

  

  The 
  results 
  reduced 
  to 
  the 
  same 
  volume 
  of 
  air 
  are 
  shown 
  

   in 
  Table 
  XIV. 
  / 
  

  

  Table 
  XIY. 
  

  

  To 
  

  

  — 
  > 
  

  

  pump 
  

  

  Date. 
  

  

  Leak 
  from 
  emanation 
  

  

  absorbed 
  by 
  Charcoal 
  

  

  Tube 
  from 
  70 
  litres 
  

  

  of 
  air. 
  

  

  Leak 
  from 
  emanation 
  

   abstracted 
  by 
  Con- 
  

   denser 
  from 
  70 
  litres 
  

   of 
  air. 
  

  

  March 
  31 
  

  

  Mav 
  7 
  

  

  •29 
  

  

  •34 
  

  

  •62 
  

   •66 
  

  

  

  so 
  that 
  

  

  amount 
  absorbed 
  from 
  the 
  air 
  by 
  charcoal 
  

   amount 
  abstracted 
  from 
  the 
  air 
  by 
  condenser 
  

  

  ' 
  31 
  1 
  Li 
  

  

  ^4 
  = 
  2 
  roughly. 
  

  

  m 
  

  

  Now 
  dealing 
  with 
  the 
  amount 
  of 
  emanation 
  given 
  off 
  i_ 
  

   the 
  solution 
  in 
  two 
  hours 
  we 
  get 
  (See 
  Tables 
  IV., 
  IX., 
  XI.) 
  

  

  amount 
  absorbed 
  by 
  charcoal 
  _ 
  2*5 
  _ 
  1*4 
  . 
  , 
  

  

  amount 
  abstracted 
  by 
  condenser 
  3*6 
  2 
  ^ 
  j» 
  

  

  so 
  that 
  in 
  each 
  case 
  the 
  condenser 
  takes 
  out 
  about 
  twice 
  as 
  

   much 
  as 
  the 
  charcoal, 
  the 
  charcoal, 
  however, 
  becoming 
  more 
  

   efficient 
  as 
  the 
  amount 
  of 
  emanation 
  in 
  the 
  air- 
  current 
  

   increases. 
  Both 
  methods, 
  therefore, 
  give 
  about 
  the 
  same 
  

   result 
  for 
  the 
  amount 
  of 
  emanation 
  in 
  the 
  air, 
  but 
  the 
  method 
  

   of 
  the 
  condenser 
  is 
  quicker 
  and 
  more 
  accurate 
  than 
  the 
  

   charcoal 
  method. 
  The 
  chief 
  disadvantages 
  of 
  the 
  charcoal 
  

  

  