﻿Tr.owhridge 
  and 
  Richards 
  — 
  Multiple 
  Spectra 
  of 
  Gases. 
  117 
  

  

  Art. 
  X. 
  — 
  The 
  Multiple 
  Spectra 
  of 
  Gases 
  ; 
  by 
  John 
  Trow- 
  

   bridge 
  and 
  Theodore 
  Wm. 
  Eichards. 
  

  

  In 
  a 
  recent 
  paper 
  upon 
  the 
  spectra 
  of 
  argon 
  we 
  have 
  shown 
  

   that 
  the 
  two 
  different 
  spectra 
  of 
  this 
  gas 
  are 
  dependent 
  

   primarily 
  upon 
  the 
  electrical 
  conditions 
  which 
  cause 
  the 
  gas 
  to 
  

   glow. 
  The 
  continuous 
  discharge 
  of 
  a 
  high 
  tension 
  accumula- 
  

   tor 
  through 
  the 
  gas 
  -produces 
  the 
  red 
  spectrum, 
  while 
  the 
  dis- 
  

   charge 
  of 
  a 
  condenser, 
  provided 
  that 
  its 
  oscillations 
  are 
  not 
  

   damped 
  by 
  the 
  resistance 
  of 
  the 
  tube, 
  or 
  other 
  resistance 
  or 
  

   impedance, 
  produces 
  the 
  blue 
  spectrum. 
  

  

  It 
  becomes 
  now 
  a 
  matter 
  of 
  great 
  interest 
  to 
  determine 
  if 
  the 
  

   same 
  conclusions 
  apply 
  to 
  other 
  gases, 
  a 
  subject 
  which 
  has 
  

   already 
  been 
  studied 
  in 
  detail 
  by 
  Wiillner 
  and 
  others. 
  The 
  

   chief 
  difference 
  between 
  our 
  work 
  and 
  the 
  earlier 
  investiga- 
  

   tions 
  are 
  : 
  first, 
  the 
  use 
  of 
  a 
  high 
  tension 
  accumulator 
  instead 
  

   of 
  an 
  electrical 
  machine 
  or 
  Ruhmkorff 
  coil 
  as 
  the 
  source 
  of 
  

   electricity; 
  and 
  secondly, 
  the 
  introduction 
  of 
  varying 
  ohmic 
  

   resistance 
  or 
  impedance 
  between 
  the 
  plates 
  of 
  the 
  condenser 
  in 
  

   order 
  to 
  study 
  the 
  damping 
  of 
  the 
  spark. 
  It 
  is 
  the 
  object 
  of 
  

   this 
  paper 
  to 
  emphasize 
  anew 
  the 
  importance 
  of 
  the 
  electrical 
  

   conditions 
  of 
  the 
  circuit, 
  and 
  to 
  call 
  attention 
  once 
  more 
  to 
  the 
  

   fact 
  that 
  the 
  behavior 
  of 
  most 
  elementary 
  gases 
  is 
  in 
  every 
  

   respect 
  similar 
  to 
  that 
  of 
  argon. 
  

  

  With 
  regard 
  to 
  the 
  spectrum 
  of 
  nitrogen, 
  it 
  has 
  been 
  known 
  

   for 
  a 
  long 
  time 
  that 
  two 
  spectra 
  could 
  be 
  obtained 
  by 
  means 
  

   of 
  appropriate 
  changes 
  in 
  the 
  density 
  of 
  the 
  gas, 
  as 
  well 
  as 
  by 
  

   the 
  introduction 
  of 
  the 
  condenser 
  ; 
  but 
  not 
  all 
  investigators 
  

   have 
  put 
  the 
  same 
  interpretation 
  upon 
  their 
  results. 
  So 
  vary- 
  

   ing 
  are 
  the 
  views, 
  that 
  Angstrom* 
  and 
  Thalenf 
  believed 
  the 
  

   familiar 
  channelled 
  spectrum 
  to 
  be 
  due 
  to 
  impurities 
  in 
  the 
  gas. 
  

   Plucker 
  and 
  Hittorf,J 
  Wiillner§ 
  and 
  SaletJ 
  have 
  proved 
  this 
  

   view 
  to 
  be 
  false, 
  but 
  they 
  had 
  not 
  at 
  hand 
  the 
  constant 
  current 
  

   of 
  high 
  tension 
  at 
  our 
  disposal 
  and 
  their 
  nitrogen 
  was 
  obtained 
  

   from 
  air 
  containing 
  argon, 
  so 
  that 
  a 
  revision 
  of 
  their 
  work 
  

   promised 
  to 
  be 
  of 
  great 
  interest. 
  

  

  With 
  our 
  Plante 
  battery 
  of 
  ten 
  thousand 
  volts 
  we 
  have 
  

   obtained 
  the 
  usual 
  two 
  different 
  spectra 
  of 
  nitrogen 
  by 
  vary- 
  

   ing 
  suitably 
  the 
  electrical 
  conditions 
  of 
  the 
  discharge. 
  By 
  

   means 
  of 
  a 
  continuous 
  discharge 
  with 
  no 
  spark 
  gap 
  or 
  brush 
  dis- 
  

  

  * 
  Pogg. 
  Annalen, 
  cxliv, 
  300. 
  

   + 
  Bull. 
  soc. 
  chim. 
  (2), 
  xxv, 
  183, 
  

  

  % 
  Roy. 
  Soc, 
  Proc, 
  xiii, 
  153. 
  Phil. 
  Mag. 
  (4), 
  xxviii, 
  64. 
  

   § 
  Pogg. 
  Ann., 
  cxxxv, 
  497, 
  cxxxvii, 
  337, 
  exlvii, 
  321, 
  cxlix, 
  103, 
  cliv, 
  149. 
  

   || 
  Ann. 
  Ohem. 
  Phys- 
  (4), 
  xxviii, 
  52. 
  Hasselberg, 
  Ames 
  and 
  others 
  have 
  also 
  

   studied 
  the 
  nitrogen 
  spectra. 
  

  

  