﻿Action 
  of 
  the 
  Radium 
  Emanation 
  upon 
  Water. 
  815 
  

  

  The 
  spectrum 
  of 
  hydrogen 
  and 
  mercury 
  disappeared, 
  and 
  

   the 
  tube 
  became 
  very 
  hard 
  and 
  showed 
  only 
  the 
  neon 
  

   spectrum. 
  

  

  Proceeding 
  in 
  this 
  way, 
  we 
  were 
  able 
  to 
  detect 
  easily 
  the 
  

   neon 
  yellow 
  line 
  when 
  Jjj- 
  c.c. 
  was 
  introduced 
  into 
  the 
  reservoir 
  

   E. 
  The 
  conditions 
  to 
  bring 
  out 
  the 
  spectrum 
  most 
  clearly 
  

   could 
  readily 
  be 
  tested 
  by 
  passing 
  a 
  discharge 
  at 
  short 
  

   intervals 
  through 
  the 
  tube 
  as 
  it 
  slowly 
  warmed 
  up 
  from 
  

   evaporation 
  of 
  the 
  liquid 
  air. 
  At 
  a 
  certain 
  stage, 
  the 
  neon 
  

   yellow 
  line 
  and 
  the 
  stronger 
  reds 
  flashed 
  out 
  clearly. 
  With 
  

   ^_ 
  c.c. 
  of 
  air 
  the 
  red 
  lines 
  of 
  neon 
  were 
  clearly 
  visible, 
  and 
  

   with 
  }- 
  c.c. 
  a 
  brilliant 
  spectrum 
  of 
  neon 
  was 
  obtained, 
  showing 
  

   most 
  of 
  the 
  lines. 
  These 
  experiments 
  were 
  repeated 
  on 
  

   several 
  occasions, 
  the 
  vacuum-tube 
  being 
  changed 
  between 
  

   each 
  experiment, 
  and 
  in 
  every 
  case 
  the 
  same 
  results 
  were 
  

   obtained. 
  

  

  According 
  to 
  the 
  measurements 
  of 
  Ramsay 
  neon 
  is 
  present 
  

   in 
  air 
  in 
  about 
  one 
  part 
  in 
  100,000 
  by 
  volume. 
  The 
  experi- 
  

   ments 
  thus 
  show 
  that 
  one 
  can 
  readily 
  detect 
  the 
  presence 
  of 
  

   neon 
  in 
  amount 
  less 
  than 
  one 
  millionth 
  of 
  a 
  cubic 
  centimetre. 
  

   It 
  is 
  quite 
  probable 
  that 
  with 
  a 
  still 
  better 
  choice 
  of 
  con- 
  

   ditions, 
  a 
  still 
  smaller 
  quantity 
  could 
  be 
  spectroscopically 
  

   detected. 
  

  

  A 
  Watts 
  binocular 
  grating 
  spectroscope 
  was 
  found 
  very 
  

   "convenient 
  for 
  a 
  rapid 
  examination 
  of 
  the 
  spectra 
  ; 
  measure- 
  

   ments 
  of 
  wave-lengths 
  were 
  carried 
  out 
  by 
  means 
  of 
  a 
  Hilger 
  

   direct-reading 
  spectroscope. 
  

  

  Experiments 
  with 
  the 
  Emanation. 
  

  

  In 
  order 
  to 
  collect 
  the 
  gases 
  formed 
  by 
  the 
  action 
  of 
  

   radium 
  emanation 
  on 
  water, 
  we 
  employed 
  a 
  method 
  very 
  

   similar 
  to 
  that 
  used 
  by 
  Cameron 
  and 
  Eamsay. 
  For 
  clearness, 
  

   we 
  shall 
  describe 
  with 
  some 
  detail 
  the 
  progress 
  of 
  a 
  complete 
  

   experiment. 
  A 
  glass 
  bulb 
  of 
  about 
  4 
  c.c. 
  capacity, 
  provided 
  

   with 
  a 
  stopcock, 
  was 
  half 
  filled 
  with 
  distilled 
  water 
  and 
  then 
  

   placed 
  in 
  an 
  evaporation-bath 
  to 
  expel 
  the 
  air 
  from 
  the 
  bulb 
  

   and 
  the 
  water. 
  The 
  stopcock 
  was 
  then 
  closed, 
  and 
  the 
  bulb 
  

   sealed 
  on 
  to 
  a 
  side-tube 
  connected 
  withi 
  the 
  mercury-pump, 
  

   as 
  shown 
  at 
  M. 
  The 
  water 
  in 
  the 
  bulb 
  was 
  frozen 
  by 
  

   surrounding 
  it 
  with 
  liquid 
  air 
  and 
  the 
  last 
  trace 
  of 
  air 
  then 
  

   pumped 
  out. 
  In 
  the 
  meantime 
  the 
  emanation, 
  corresponding 
  

   to 
  the 
  equilibrium 
  amount 
  from 
  150 
  mg. 
  of 
  radium, 
  was 
  

   carefully 
  purified 
  after 
  the 
  manner 
  described 
  in 
  a 
  previous 
  

   paper 
  and 
  stored 
  in 
  the 
  U-tube. 
  By 
  opening 
  the 
  stopcock 
  B 
  

   the 
  emanation 
  was 
  then 
  all 
  condensed 
  in 
  the 
  frozen 
  bulb. 
  

   The 
  stopcock 
  was 
  thereupon 
  closed 
  and 
  surrounded 
  by 
  a 
  

  

  