﻿Spectrum 
  of 
  the 
  Radium 
  Emanation. 
  315 
  

  

  brilliancy 
  o£ 
  the 
  phosphorescence 
  of 
  the 
  glass, 
  practically 
  all 
  

   the 
  lines 
  except 
  those 
  due 
  to 
  hydrogen 
  vanished, 
  The 
  colour 
  

   of 
  the 
  discharge 
  then 
  completely 
  changed 
  to 
  a 
  pale 
  rose, 
  and 
  

   the 
  tube 
  became 
  harder. 
  At 
  the 
  moment 
  of 
  volatilization 
  

   the 
  emanation 
  lines 
  flashed 
  out 
  again. 
  

  

  The 
  hydrogen 
  lines 
  came 
  out 
  more 
  strongly 
  when 
  the 
  

   emanation 
  was 
  condensed. 
  In 
  previous 
  experiments 
  with 
  

   the 
  electrodeless 
  discharge, 
  the 
  hydrogen 
  lines 
  had 
  been 
  

   absent. 
  Their 
  occurrence 
  in 
  the 
  present 
  experiment 
  was 
  

   without 
  doubt 
  due 
  to 
  the 
  liberation 
  of 
  hydrogen 
  from 
  the 
  

   platinum 
  electrodes 
  when 
  a 
  strong 
  discharge 
  was 
  passed. 
  

   This 
  is 
  borne 
  oat 
  by 
  the 
  results 
  of 
  another 
  experiment 
  recorded 
  

   later. 
  The 
  emanation 
  was 
  momentarily 
  condensed 
  at 
  intervals 
  

   during 
  the 
  experiment 
  in 
  the 
  side 
  tube. 
  From 
  observations 
  

   of 
  the 
  brilliancy 
  of 
  the 
  phosphorescence 
  at 
  condensation, 
  it 
  

   was 
  noted 
  that 
  the 
  amount 
  of 
  the 
  free 
  emanation 
  in 
  the 
  tube 
  

   gradually 
  diminished 
  with 
  increasing 
  time 
  of 
  discharge, 
  while 
  

   the 
  intensity 
  of 
  the 
  emanation 
  spectrum 
  decreased 
  relatively 
  

   to 
  that 
  of 
  hydrogen. 
  The 
  emanation 
  lines, 
  however, 
  persisted 
  

   to 
  the 
  close 
  of 
  the 
  experiment, 
  when 
  practically 
  all 
  the 
  

   emanation 
  had 
  been 
  driven 
  into 
  the 
  walls 
  of 
  the 
  tube. 
  From 
  

   observations 
  of 
  the 
  phosphorescence, 
  it 
  was 
  evident 
  that 
  the 
  

   emanation 
  was 
  approximately 
  uniformly 
  distributed 
  along 
  

   the 
  line 
  of 
  discharge. 
  As 
  the 
  discharge' 
  had 
  been 
  reversed 
  at 
  

   intervals 
  during 
  the 
  experiment, 
  it 
  was 
  difficult 
  to 
  be 
  certain 
  

   whether 
  there 
  had 
  been 
  any 
  considerable 
  absorption 
  of 
  the 
  

   emanation 
  by 
  the 
  electrodes. 
  The 
  occlusion 
  of 
  the 
  emanation 
  

   had 
  been 
  observed 
  previously 
  on 
  several 
  occasions 
  in 
  the 
  

   capillary 
  tube 
  using 
  the 
  electrodeless 
  discharge 
  (see 
  previous 
  

   paper) 
  . 
  It 
  seems 
  probable 
  that 
  the 
  emanation 
  is 
  in 
  some 
  way 
  

   driven 
  into 
  the 
  walls 
  of 
  the 
  tube 
  by 
  the 
  discharge. 
  This 
  

   effect 
  is 
  no 
  doubt 
  similar 
  to 
  that 
  recorded 
  by 
  Campbell 
  

   ►Swinton 
  for 
  ordinary 
  gases. 
  It 
  is 
  difficult 
  to 
  remove 
  such 
  

   occluded 
  emanation 
  even 
  by 
  strongly 
  heating 
  the 
  glass. 
  

  

  After 
  three 
  days, 
  the 
  tube 
  was 
  very 
  much 
  darkened 
  by 
  the 
  

   emanation, 
  and 
  it 
  was 
  necessary 
  to 
  get 
  rid 
  of 
  the 
  blackening 
  

   by 
  heat 
  in 
  order 
  to 
  observe 
  the 
  spectrum. 
  The 
  main 
  helium 
  

   lines 
  were 
  observed, 
  but 
  w 
  r 
  ere 
  faint 
  in 
  comparison 
  with 
  the 
  

   hydrogen 
  lines. 
  

  

  After 
  a 
  week's 
  interval, 
  the 
  spectrum-tube 
  was 
  again 
  

   attached 
  to 
  the 
  pump 
  and 
  thoroughly 
  heated 
  above 
  the 
  tem- 
  

   perature 
  of 
  thermo-luminescence 
  in 
  order 
  to 
  make 
  the 
  glass 
  

   as 
  transparent 
  as 
  possible. 
  The 
  spectrum-tube 
  was 
  exhausted, 
  

   care 
  being 
  taken 
  by 
  heating 
  the 
  tube 
  and 
  by 
  passage 
  of 
  a 
  

  

  Y2 
  

  

  