﻿Trowbridge 
  and 
  Richards 
  — 
  The 
  Spectra 
  of 
  Argon. 
  17 
  

  

  emit 
  the 
  humming 
  sound 
  peculiar 
  to 
  it, 
  the 
  beautiful 
  blue 
  glow 
  

   so 
  characteristic 
  of 
  argon 
  immediately 
  appeared. 
  

  

  If 
  this 
  light 
  is 
  examined 
  by 
  a 
  revolving 
  mirror 
  it 
  is 
  seen 
  to 
  

   consist 
  of 
  intermittent 
  discharges. 
  The 
  battery 
  charges 
  the 
  

   condenser 
  to 
  the 
  potential 
  necessary 
  to 
  produce 
  a 
  sparkbetween 
  

   the 
  terminal 
  of 
  the 
  spark 
  gap. 
  The 
  discharge 
  of 
  this 
  accumu- 
  

   lated 
  electricity 
  is 
  produced 
  in 
  the 
  tube 
  and 
  then 
  the 
  operation 
  

   is 
  repeated. 
  The 
  time 
  interval 
  between 
  the 
  discharges 
  is 
  evi- 
  

   dently 
  a 
  function 
  of 
  the 
  capacity 
  of 
  the 
  condenser, 
  as 
  well 
  as 
  

   of 
  the 
  electromotive 
  force 
  of 
  the 
  battery 
  and 
  the 
  resistance 
  

   between 
  it 
  and 
  the 
  condenser. 
  

  

  The 
  accurate 
  determinations 
  of 
  the 
  potential 
  and 
  current 
  

   strength 
  of 
  the 
  intermittent 
  blue 
  discharge 
  is 
  a 
  matter 
  of 
  some 
  

   difficulty; 
  and 
  at 
  present 
  we 
  fee] 
  hardly 
  in 
  position 
  to 
  make 
  a 
  

   definite 
  statement 
  regarding 
  these 
  measurements. 
  However, 
  

   the 
  potential 
  required 
  certainly 
  cannot 
  be 
  greater 
  than 
  two 
  

   thousand 
  volts, 
  — 
  the 
  electromotive 
  force 
  of 
  the 
  battery 
  which 
  

   will 
  easily 
  produce 
  the 
  blue 
  glow. 
  Here 
  again, 
  Crookes's 
  esti 
  

   mate 
  of 
  far 
  above 
  27,000 
  volts 
  was- 
  very 
  much 
  too 
  large. 
  

  

  Since 
  it 
  is 
  necessary 
  to 
  employ 
  a 
  condenser 
  to 
  produce 
  the 
  

   blue 
  spectrum 
  of 
  argon, 
  we 
  were 
  led 
  to 
  examine 
  the 
  electrical 
  

   conditions 
  which 
  are 
  necessary 
  for 
  the 
  discharge. 
  In 
  the 
  cir- 
  

   cuit 
  with 
  the 
  tube 
  containing 
  argon, 
  between 
  the 
  tube 
  and 
  one 
  

   of 
  the 
  plates 
  of 
  the 
  condenser, 
  we 
  first 
  interposed 
  a 
  small 
  coil 
  

   of 
  about 
  eight 
  ohms 
  resistance, 
  having 
  a 
  self-induction 
  of 
  *015 
  

   of 
  a 
  henry. 
  The 
  blue 
  glow 
  changed 
  to 
  the 
  red 
  glow. 
  We 
  

   then 
  modified 
  the 
  self-induction 
  and 
  discovered 
  that 
  even 
  the 
  

   self-induction 
  of 
  the 
  leads 
  to 
  the 
  tube, 
  which 
  consisted 
  of 
  a 
  few 
  

   feet 
  of 
  uncoiled 
  wire, 
  undoubtedly 
  modified 
  the 
  blue 
  discharge, 
  

   for 
  an 
  amount 
  of 
  induction 
  equivalent 
  to 
  -000051 
  henry 
  had 
  a 
  

   marked 
  effect 
  in 
  diminishing 
  the 
  brilliancy 
  of 
  the 
  blue 
  glow. 
  

  

  A 
  comparatively 
  small 
  ohmic 
  resistance 
  substituted 
  for 
  the 
  

   impedance 
  of 
  the 
  self-induction 
  between 
  the 
  tube 
  and 
  one 
  

   plate 
  of 
  the 
  condenser 
  produced 
  precisely 
  the 
  same 
  effect 
  as 
  

   this 
  coil, 
  causing 
  a 
  complete 
  transformation 
  from 
  blue 
  to 
  red. 
  

   The 
  change 
  from 
  blue 
  to 
  red 
  is 
  so 
  marked 
  that 
  a 
  tube 
  of 
  argon 
  

   may 
  well 
  serve 
  as 
  an 
  inductometer 
  of 
  some 
  sensitiveness, 
  as 
  

   well 
  as 
  a 
  means 
  of 
  comparing 
  the 
  influence 
  of 
  self-induction 
  

   with 
  ohmic 
  resistance. 
  The 
  effect 
  of 
  impedance 
  or 
  resistance 
  

   must 
  be 
  to 
  prolong 
  or 
  to 
  damp 
  the 
  oscillations 
  of 
  the 
  condenser 
  

   discharge. 
  Indeed, 
  the 
  resistance 
  of 
  the 
  tube 
  itself 
  may 
  be 
  so 
  

   great 
  as 
  to 
  damp 
  the 
  oscillations 
  without 
  the 
  need 
  of 
  the 
  intro- 
  

   duction 
  of 
  outside 
  resistance 
  or 
  self-induction 
  ; 
  therefore 
  argon 
  

   at 
  high 
  tension 
  gives 
  the 
  red 
  glow 
  with 
  a 
  condenser 
  and 
  rate 
  of 
  

   oscillations 
  which 
  are 
  quite 
  capable 
  of 
  producing 
  the 
  blue 
  glow 
  

   in 
  a 
  tube 
  of 
  lower 
  tension. 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Yol. 
  Ill, 
  No. 
  13. 
  — 
  January, 
  1897. 
  

  

  