﻿

  Experiments 
  with 
  the 
  Radium 
  Emanation. 
  301 
  

  

  They 
  conclude 
  that 
  the 
  volume 
  of* 
  the 
  emanation 
  is 
  about 
  

   7 
  # 
  07 
  cubic 
  mms., 
  and 
  suggest 
  that 
  the 
  smaller 
  value 
  initially 
  

   obtained 
  by 
  Ramsay 
  and 
  Soddy 
  was 
  due 
  to 
  the 
  greater 
  part 
  of 
  

   the 
  emanation 
  being 
  pumped 
  off 
  during 
  the 
  experiment. 
  The 
  

   volume 
  of 
  the 
  emanation 
  (7*07 
  cubic 
  mms.) 
  obtained 
  in 
  their 
  

   experiments 
  is 
  of 
  quite 
  a 
  different 
  order 
  from 
  the 
  calculated 
  

   volume 
  (0*57 
  cubic 
  mm.). 
  It 
  is 
  of 
  importance 
  to 
  determine 
  

   the 
  cause 
  of 
  this 
  wide 
  discrepancy 
  between 
  theory 
  and 
  

   experiment. 
  If* 
  the 
  experimental 
  value 
  proves 
  correct, 
  it 
  

   would 
  indicate 
  that 
  much 
  of 
  the 
  radioactive 
  data 
  and 
  of 
  the 
  

   theory 
  on 
  which 
  the 
  calculations 
  are 
  based 
  is 
  seriously 
  in 
  

   error. 
  Apart 
  from 
  the 
  interest 
  attaching 
  to 
  the 
  comparison 
  

   of 
  theory 
  with 
  experiment, 
  the 
  separation 
  of 
  the 
  radium 
  

   emanation 
  in 
  a 
  pure 
  state 
  is 
  now 
  of 
  the 
  highest 
  practical 
  

   importance. 
  Not 
  only 
  is 
  pure 
  emanation 
  required 
  in 
  order 
  

   to 
  study 
  carefully 
  the 
  physical 
  and 
  chemical 
  properties 
  of 
  

   this 
  remarkable 
  gas, 
  but 
  it 
  is 
  also 
  required 
  in 
  the 
  experiments 
  

   similar 
  to 
  those 
  initiated 
  by 
  Ramsay 
  and 
  Cameron 
  *, 
  where 
  the 
  

   radium 
  emanation 
  is 
  added 
  to 
  different 
  solutions 
  and 
  the 
  

   resulting 
  products 
  determined. 
  

  

  By 
  the 
  generosity 
  of 
  the 
  Academy 
  of 
  Sciences 
  of 
  Vienna, 
  

   I 
  was 
  recently 
  loaned 
  a 
  preparation 
  of 
  radium 
  containing 
  

   about 
  250 
  milligrams 
  of 
  radium. 
  Experiments 
  were 
  imme- 
  

   diately 
  begun 
  in 
  order 
  to 
  purify 
  the 
  emanation 
  produced 
  by 
  

   it, 
  and 
  to 
  determine 
  its 
  volume. 
  In 
  all, 
  a 
  large 
  number 
  of 
  

   experiments 
  have 
  been 
  made, 
  but 
  for 
  brevity 
  I 
  shall 
  here 
  only 
  

   indicate 
  the 
  general 
  results 
  obtained 
  in 
  these 
  investigations. 
  

  

  Separation 
  of 
  tlie 
  Emanation. 
  

  

  There 
  are 
  two 
  general 
  methods 
  of 
  obtaining 
  the 
  emanation 
  

   from 
  preparations 
  of 
  radium, 
  viz., 
  by 
  heat 
  or 
  by 
  solution. 
  

   Both 
  of 
  these 
  methods 
  have 
  been 
  used. 
  In 
  the 
  earlier 
  experi- 
  

   ments, 
  the 
  radium 
  preparation 
  was 
  placed 
  in 
  a 
  thin 
  quartz 
  

   tube 
  which 
  was 
  enclosed 
  in 
  a 
  larger 
  quartz 
  tube. 
  The 
  latter 
  

   was 
  heated 
  to 
  the 
  desired 
  temperature 
  by 
  means 
  of 
  an 
  electric 
  

   furnace. 
  The 
  emanation 
  is 
  practically 
  all 
  released 
  at 
  the 
  

   temperature 
  of 
  fusion 
  (about 
  830° 
  C.) 
  f 
  of 
  barium-radium 
  

   chloride. 
  After 
  the 
  preliminary 
  heating, 
  a 
  very 
  small 
  

   quantity 
  of 
  intensely 
  radioactive 
  gas 
  was 
  released, 
  the 
  volume 
  

   of 
  which 
  was 
  so 
  small 
  that 
  it 
  was 
  found 
  necessary 
  to 
  add 
  a 
  

   small 
  quantity 
  of 
  hydrogen 
  or 
  oxygen 
  in 
  order 
  to 
  pump 
  off 
  

   the 
  emanation 
  completely. 
  In 
  later 
  experiments, 
  the 
  radium 
  

   preparation 
  was 
  in 
  solution 
  in 
  a 
  quartz 
  tube. 
  The 
  emanation 
  

  

  * 
  Journ. 
  Chem. 
  Soc. 
  p. 
  1593 
  (1907). 
  

  

  t 
  See 
  paper 
  by 
  L. 
  Kolowrat, 
  Le 
  Radium, 
  Sept. 
  1907. 
  

  

  