﻿Radium 
  Emanation 
  in 
  the 
  Atmosphere. 
  607 
  

  

  As 
  the 
  method 
  of 
  drying 
  the 
  air 
  may 
  be 
  open 
  to 
  criticism 
  

   (see 
  Method 
  I.) 
  I 
  tried 
  various 
  methods 
  of 
  drying. 
  

  

  Since 
  60 
  litres 
  of 
  air 
  at 
  15° 
  C. 
  and 
  of 
  dew-point 
  10° 
  C. 
  

   contain 
  only 
  '5 
  grm. 
  of 
  water 
  it 
  was 
  thought 
  that 
  if 
  the 
  air 
  

   were 
  allowed 
  to 
  pass 
  through 
  the 
  condenser 
  undried 
  it 
  would 
  

   not 
  choke 
  it. 
  I 
  therefore 
  tried 
  one 
  experiment 
  in 
  which 
  no 
  

   drying-tube 
  was 
  used 
  at 
  all, 
  but 
  in 
  half 
  an 
  hour 
  the 
  air- 
  

   current 
  began 
  to 
  decrease, 
  and 
  before 
  the 
  hour 
  was 
  up 
  

   the 
  condenser 
  was 
  quite 
  choked 
  and 
  the 
  experiment 
  came 
  

   to 
  an 
  end. 
  

  

  Another 
  plan 
  was 
  to 
  pass 
  the 
  air 
  through 
  a 
  long 
  spiral 
  of 
  

   composition 
  tubing 
  500 
  cms. 
  long 
  immersed 
  in 
  a 
  freezing- 
  

   mixture 
  of 
  salt 
  and 
  ice 
  (at 
  —18° 
  C), 
  but 
  even 
  with 
  this 
  

   arrangement 
  the 
  condenser 
  very 
  nearly 
  choked. 
  A 
  subse- 
  

   quent 
  examination 
  of 
  the 
  spiral 
  showed 
  that 
  very 
  little, 
  

   if 
  any, 
  water 
  had 
  been 
  condensed 
  by 
  it 
  out 
  of 
  the 
  current 
  

   of 
  air. 
  

  

  Still 
  another 
  plan 
  was 
  to 
  use 
  strong 
  sulphuric 
  acid 
  as 
  a 
  

   dehydrator. 
  Two 
  bottles 
  were 
  three 
  parts 
  filled 
  with 
  acid 
  

   (400 
  c.c. 
  were 
  used) 
  and 
  fitted 
  with 
  delivery-tubes 
  so 
  that 
  

   air 
  bubbled 
  through 
  a 
  total 
  length 
  of 
  about 
  20 
  cm. 
  of 
  acid. 
  

   This 
  worked 
  quite 
  satisfactorily. 
  The 
  results 
  are 
  given 
  below. 
  

   Just 
  as 
  in 
  the 
  case 
  of 
  the 
  OaCl 
  2 
  tubes 
  I 
  never 
  used 
  a 
  tube 
  

   for 
  the 
  air 
  that 
  I 
  had 
  already 
  used 
  for 
  the 
  radium 
  solution, 
  

   so 
  in 
  this 
  case 
  any 
  batch 
  of 
  acid 
  used 
  for 
  the 
  solution 
  

   was 
  put 
  away 
  and 
  a 
  fresh 
  batch 
  used 
  for 
  the 
  next 
  air 
  

   reading. 
  

  

  It 
  would 
  have 
  been 
  better 
  if 
  two 
  condensers 
  had 
  been 
  used 
  

   just 
  as 
  in 
  Method 
  I. 
  two 
  charcoal 
  tubes 
  were 
  used. 
  Simul- 
  

   taneous 
  runs 
  of 
  air 
  and 
  air 
  plus 
  solution 
  could 
  then 
  have 
  been 
  

   taken, 
  but 
  the 
  large 
  quantity 
  of 
  liquid 
  air 
  required 
  precluded 
  

   this. 
  Only 
  on 
  one 
  occasion 
  (May 
  16) 
  did 
  I 
  do 
  two 
  liquid 
  

   air 
  experiments 
  on 
  the 
  same 
  day. 
  

  

  The 
  following 
  tables 
  contain 
  the 
  experimental 
  results 
  

   obtained 
  with 
  the 
  condenser. 
  None 
  of 
  the 
  experiments 
  made 
  

   are 
  omitted. 
  Details 
  of 
  the 
  weather, 
  the 
  height 
  of 
  the 
  

   barometer, 
  and 
  the 
  time 
  of 
  day 
  of 
  the 
  experiment 
  are 
  inserted 
  

   in 
  order 
  that 
  any 
  effect 
  on 
  the 
  amount 
  of 
  emanation 
  caused 
  

   by 
  the 
  weather 
  or 
  time 
  of 
  day 
  could 
  be 
  detected. 
  The 
  leaks 
  

   are 
  given 
  in 
  scale-divisions 
  per. 
  minute. 
  It 
  will 
  be 
  noticed 
  

   that 
  the 
  air 
  leak 
  is 
  subject 
  to 
  considerable 
  variations. 
  These 
  

   variations 
  were 
  sometimes 
  caused 
  by 
  the 
  proximity 
  of 
  radium 
  

   (in 
  sealed 
  tubes) 
  used 
  by 
  other 
  experimenters. 
  

  

  