﻿Higli-Frequency 
  Discharges 
  in 
  Geissler 
  Tales, 
  977 
  

  

  was 
  greatly 
  enhanced 
  relatively 
  to 
  the 
  secondary 
  or 
  many- 
  

   lined 
  spectrum, 
  when 
  larger 
  current 
  values 
  were 
  used. 
  This 
  

   is 
  a 
  similar 
  result 
  to 
  that 
  obtained 
  with 
  increased 
  currents 
  in 
  

   hydrogen 
  when 
  the 
  induction-coil 
  discharge 
  is 
  used. 
  The 
  

   appearance 
  o£ 
  the 
  tube, 
  particularly 
  with 
  the 
  Poulsen 
  dis- 
  

   charge, 
  is 
  very 
  striking. 
  At 
  low 
  currents 
  the 
  tube 
  has 
  

   somewhat 
  o£ 
  a 
  bluish-lavender 
  colour, 
  whilst 
  at 
  high 
  currents 
  

   it 
  glows 
  very 
  strongly 
  with 
  a 
  strong 
  ruddy 
  glow. 
  With 
  

   gradually 
  increasing 
  current-values 
  the 
  secondary 
  spectrum 
  

   appeared 
  to 
  increase 
  uniformly, 
  but 
  the 
  primary 
  spectrum 
  

   showed 
  marked 
  selectivity, 
  the 
  a, 
  /3, 
  and 
  y 
  lines 
  increasing 
  

   in 
  descending 
  order 
  of 
  magnitude 
  respectively. 
  Thus 
  with 
  

   the 
  Poulsen 
  high-frequency 
  discharge 
  we 
  obtain 
  results 
  

   strictly 
  compatible 
  with 
  those 
  obtained 
  by 
  Nutting 
  and 
  

   Tugman*, 
  using 
  the 
  induction 
  coil 
  with 
  varying 
  currents. 
  

   The 
  appearance 
  of 
  the 
  discharge 
  can 
  well 
  be 
  judged 
  from 
  

   examination 
  of 
  the 
  four 
  spectrograms 
  5 
  a, 
  5 
  b, 
  5 
  e, 
  and 
  5 
  d 
  

   (PL 
  XXII.) 
  taken 
  with 
  a 
  discharge 
  of 
  oscillation 
  frequency 
  

   0'2 
  X 
  10 
  6 
  per 
  second 
  at 
  1 
  mm. 
  pressure, 
  a 
  and 
  b 
  were 
  arranged 
  

   to 
  have 
  the 
  same 
  approximate 
  intensity 
  of 
  series 
  lines, 
  and 
  it 
  

   will 
  be 
  noticed 
  that 
  at 
  the 
  lower 
  current 
  density 
  the 
  secondary 
  

   spectrum 
  is 
  much 
  more 
  prominent 
  than 
  at 
  the 
  higher 
  current 
  

   density. 
  The 
  same 
  result 
  is 
  shown 
  in 
  c 
  and 
  d, 
  where 
  the 
  inten- 
  

   sity 
  of 
  the 
  secondary 
  spectrum 
  was 
  maintained 
  constant, 
  whilst 
  

   it 
  will 
  be 
  noticed 
  that 
  the 
  primary 
  spectrum 
  is 
  much 
  more 
  

   pronounced 
  at 
  the 
  higher 
  currents. 
  Exactly 
  analogous 
  effects 
  

   were 
  noted 
  in 
  the 
  tube 
  of 
  hydrogen 
  with 
  internal 
  electrodes. 
  

   At 
  higher 
  pressures 
  the 
  external 
  electrode 
  bulbs 
  were 
  rich 
  

   in 
  the 
  secondary 
  spectrum, 
  but 
  showed 
  the 
  primary 
  spectrum 
  

   very 
  feebly. 
  When 
  the 
  pressure 
  fell 
  below 
  the 
  critical 
  value 
  

   mentioned 
  above, 
  the 
  bulbs 
  became 
  decidedly 
  redder 
  in 
  colour, 
  

   owing 
  to 
  an 
  increased 
  selective 
  admixture 
  of 
  the 
  primary 
  

   spectrum. 
  This 
  result 
  bears 
  close 
  resemblance 
  to 
  that 
  obtained 
  

   under 
  similar 
  circumstances 
  with 
  nitrogen. 
  

  

  Oxygen. 
  

  

  The 
  oxygen 
  was 
  prepared 
  by 
  heating 
  potassium 
  perman- 
  

   ganate 
  in 
  a 
  glass 
  tube 
  sealed 
  on 
  to 
  the 
  apparatus. 
  The 
  exit 
  

   tube 
  from 
  the 
  permanganate 
  tube 
  was 
  plugged 
  with 
  glass-wool 
  

   to 
  prevent 
  escape 
  of 
  the 
  reduced 
  permanganate 
  into 
  the 
  rest 
  

   of 
  the 
  apparatus. 
  Much 
  trouble 
  was 
  experienced 
  from 
  the 
  

   presence 
  of 
  water 
  in 
  the 
  permanganate, 
  presumably 
  in 
  oc- 
  

   cluded 
  form. 
  It 
  was 
  found 
  that 
  this 
  was 
  almost 
  wholly 
  

   removed 
  by 
  heating 
  the 
  permanganate 
  in 
  an 
  oven 
  at 
  110° 
  C. 
  

   for 
  18 
  hours 
  previous 
  to 
  use. 
  Any 
  remaining 
  moisture 
  was 
  

  

  * 
  Astroph. 
  Journ. 
  xxxi. 
  1910, 
  pp. 
  62-75. 
  

  

  