﻿118 
  Trowbridge 
  and 
  Richards 
  — 
  Multiple 
  Spectra 
  of 
  Gas.es. 
  

  

  charge 
  in 
  the 
  circuit 
  through 
  nitrogen 
  under 
  varying 
  pressure, 
  

   we 
  always 
  obtained 
  the 
  channelled 
  spectrum. 
  The 
  glow 
  in 
  

   the 
  capillary 
  tube, 
  as 
  well 
  as 
  the 
  positive 
  and 
  negative 
  light, 
  

   was 
  of 
  a 
  delicate 
  pink 
  color 
  under 
  these 
  conditions 
  ; 
  a 
  color 
  

   not 
  unlike 
  the 
  red 
  glow 
  of 
  argon. 
  When 
  an 
  air-gap, 
  over 
  

   which 
  the 
  battery 
  discharges 
  in 
  a 
  brush, 
  is 
  introduced 
  into 
  this 
  

   circuit, 
  the 
  glow 
  becomes 
  more 
  violet 
  in 
  tinge, 
  and 
  the 
  spec- 
  

   troscope 
  shows 
  that 
  the 
  red 
  bands 
  almost 
  if 
  not 
  wholly 
  disap- 
  

   pear, 
  while 
  the 
  blue 
  and 
  green 
  ones 
  retain 
  their 
  positions. 
  

   Under 
  these 
  conditions 
  the 
  capillary 
  tube 
  is 
  filled 
  with 
  a 
  pure 
  

   blue 
  glow, 
  less 
  intense 
  and 
  vivid 
  than 
  that 
  of 
  the 
  argon, 
  how- 
  

   ever. 
  

  

  When 
  the 
  condenser 
  is 
  introduced, 
  the 
  whole 
  appearance 
  of 
  

   the 
  tube 
  is 
  utterly 
  transformed. 
  The 
  blue 
  color 
  of 
  the 
  tube 
  at 
  

   once 
  changes 
  to 
  a 
  rich 
  bluish 
  green, 
  and 
  the 
  channelled 
  spec- 
  

   trum 
  gives 
  place 
  to 
  bright 
  lines, 
  already 
  well 
  known 
  and 
  

   mapped. 
  This 
  line 
  spectrum 
  corresponds 
  to 
  the 
  blue 
  spectrum 
  

   of 
  argon. 
  When 
  the 
  oscillations 
  of 
  the 
  condenser-discharge 
  

   are 
  damped 
  by 
  means 
  of 
  a 
  suitable 
  resistance 
  or 
  self-induction 
  

   interposed 
  between 
  the 
  condenser 
  plates, 
  a 
  channelled 
  spec- 
  

   trum 
  reappears; 
  but 
  in 
  this 
  case 
  the 
  glow 
  in 
  the 
  tube 
  is 
  of 
  a 
  

   bluish 
  white 
  color, 
  the 
  positive 
  and 
  negative 
  lights 
  being 
  of 
  a 
  

   bright 
  yellow. 
  Whether 
  or 
  not 
  this 
  channelled 
  spectrum 
  is, 
  

   as 
  it 
  seems, 
  exactly 
  like 
  the 
  one 
  obtained 
  by 
  means 
  of 
  a 
  con- 
  

   tinuous 
  discharge, 
  photographic 
  measurement 
  will 
  show. 
  This 
  

   last 
  appearance 
  is 
  probably 
  the 
  usual 
  one 
  obtained 
  by 
  means 
  

   of 
  the 
  Ruhmkorff 
  coil, 
  for 
  then 
  the 
  oscillations 
  induced 
  by 
  

   the 
  primary 
  condenser 
  are 
  damped 
  by 
  the 
  impedance 
  of 
  the 
  

   secondary 
  coil 
  and 
  the 
  resistance 
  of 
  the 
  tube. 
  

  

  The 
  spectrum 
  of 
  hydrogen 
  is 
  usually 
  supposed 
  to 
  consist 
  of 
  

   four 
  bright 
  lines, 
  Ha 
  6563*0 
  (C), 
  H/3 
  4861-5 
  (F), 
  H? 
  4340*7 
  

   (G 
  1 
  ), 
  HS 
  4101-9 
  (h), 
  as 
  well 
  as 
  several 
  in 
  the 
  extreme 
  violet 
  

   and 
  ultra 
  violet.' 
  5 
  * 
  

  

  Other 
  spectra 
  have 
  been 
  observed 
  also 
  ; 
  but 
  owing 
  to 
  the 
  

   partial 
  understanding 
  of 
  the 
  conditions 
  required 
  to 
  produce 
  

   them, 
  the 
  voluminous 
  literaturef 
  upon 
  the 
  subject 
  leaves 
  a 
  

   confused 
  idea 
  in 
  the 
  mind 
  of 
  the 
  reader. 
  The 
  continuous 
  

   discharge 
  of 
  a 
  high 
  tension 
  accumulator 
  through 
  hydrogen 
  

   gas 
  at 
  tensions 
  varying 
  from 
  0-05 
  mm 
  to 
  3 
  mm 
  and 
  more 
  yields 
  a 
  

   beautiful 
  white 
  glow 
  in 
  the 
  capillary 
  of 
  a 
  Geissler 
  tube, 
  while 
  

   the 
  strata 
  in 
  the 
  positive 
  and 
  negative 
  light 
  are 
  often 
  alter- 
  

   nately 
  pale 
  pink 
  and 
  pale 
  blue. 
  When 
  examined 
  by 
  a 
  spec- 
  

   troscope 
  with 
  a 
  broad 
  slit, 
  the 
  light 
  from 
  this 
  discharge 
  appears 
  

  

  * 
  Ames, 
  Phil. 
  Mag. 
  (5), 
  xxx, 
  p. 
  48 
  (1890). 
  

  

  f 
  Angstrom, 
  Vogel, 
  Lockyer, 
  Fievez, 
  Wiedemann, 
  Huggins, 
  Wiillner, 
  Hassel- 
  

   berg, 
  Balmer, 
  Griinwald, 
  Villari, 
  Schuster, 
  Salet, 
  Smyth 
  and 
  others. 
  For 
  refer- 
  

   ences 
  see 
  0. 
  Dammer; 
  Anorgan. 
  Chem. 
  i, 
  369. 
  

  

  