﻿Trowbridge 
  and 
  Richards 
  — 
  The 
  Spectra 
  of 
  Argon. 
  19 
  

  

  the 
  red 
  glow 
  in 
  any 
  tube 
  from 
  the 
  continuous 
  discharge 
  of 
  a 
  

   constant 
  battery 
  was 
  apparently 
  not 
  open 
  to 
  him. 
  

  

  By 
  taking 
  out 
  all 
  resistances 
  except 
  the 
  spectrum 
  tube, 
  and 
  

   sending 
  an 
  exceedingly 
  strong 
  current 
  through 
  the 
  tube 
  for 
  

   very 
  brief 
  intervals 
  of 
  time, 
  we 
  have 
  been 
  able 
  to 
  cause 
  the 
  

   blue 
  glow; 
  but 
  it 
  seems 
  probable 
  that 
  under 
  these 
  conditions 
  

   the 
  capacity 
  of 
  the 
  battery 
  itself 
  engenders 
  oscillations 
  which 
  

   are 
  no 
  longer 
  damped 
  by 
  interposed 
  resistance. 
  Whether 
  the 
  

   blue 
  glow 
  with 
  its 
  accompanying 
  change 
  of 
  spectrum 
  is 
  due 
  

   merely 
  to 
  the 
  great 
  quantity 
  of 
  electricity 
  discharged 
  in 
  a 
  very 
  

   short 
  space 
  of 
  time, 
  or 
  to 
  some 
  property 
  intrinsic 
  in 
  the 
  to-and- 
  

   fro 
  motion 
  of 
  the 
  oscillatory 
  discharge, 
  is 
  a 
  question, 
  which 
  we 
  

   hope 
  soon 
  to 
  answer. 
  The 
  red 
  glow, 
  if 
  caused 
  by 
  oscillations 
  

   at 
  all, 
  must 
  be 
  caused 
  by 
  oscillations 
  within 
  the 
  Geissler 
  tube 
  

   itself 
  ;* 
  for 
  all 
  outside 
  oscillations 
  are 
  cut 
  off 
  by 
  the 
  large 
  

   resistance 
  between 
  the 
  battery 
  and 
  the 
  tube. 
  

  

  The 
  effect 
  of 
  the 
  oscillatory 
  discharge 
  in 
  producing 
  the 
  blue 
  

   spectrum 
  of 
  argon 
  can 
  also 
  be 
  shown 
  by 
  the 
  use 
  of 
  an 
  electri- 
  

   cal 
  machine. 
  If 
  the 
  terminals 
  of 
  the 
  tube 
  containing 
  argon 
  

   are 
  connected 
  with 
  the 
  terminals 
  of 
  an 
  electrical 
  machine, 
  the 
  

   pure 
  red 
  spectrum 
  is 
  obtained. 
  If 
  a 
  spark 
  gap 
  is 
  interposed 
  

   in 
  such 
  a 
  manner 
  that 
  a 
  condenser 
  charged 
  by 
  the 
  machine 
  can 
  

   discharge 
  through 
  the 
  tube, 
  the 
  blue 
  discharge 
  immediately 
  

   results. 
  The 
  condenser 
  discharge 
  oscillates 
  through 
  the 
  gas. 
  

  

  The 
  oscillatory 
  discharge 
  of 
  the 
  condenser 
  is 
  evidently 
  an 
  

   important 
  factor 
  in 
  producing 
  the 
  blue 
  spectrum 
  of 
  argon. 
  

   According 
  to 
  Lord 
  Kelvin's 
  law, 
  if 
  R 
  denotes 
  the 
  resistance 
  of 
  

   the 
  circuit, 
  L, 
  the 
  self-induction, 
  and 
  C 
  the 
  capacity 
  of 
  the 
  cir- 
  

   cuit, 
  the 
  discharge 
  of 
  the 
  condenser 
  becomes 
  non-oscillatory 
  when 
  

  

  R 
  = 
  y 
  — 
  . 
  It 
  may 
  be, 
  therefore, 
  that 
  an 
  estimate 
  of 
  the 
  

  

  resistance 
  in 
  the 
  tube 
  can 
  be 
  obtained 
  by 
  measuring 
  the 
  self- 
  

   induction 
  which 
  is 
  required 
  to 
  change 
  from 
  the 
  blue 
  discharge 
  

   to 
  the 
  red. 
  

  

  When 
  the 
  tube 
  containing 
  argon 
  at 
  a 
  suitable 
  pressure 
  is 
  

   brought 
  near 
  a 
  Hertz 
  oscillator, 
  giving 
  a 
  rate 
  of 
  about 
  

   115,000,000 
  oscillations 
  per 
  second, 
  it 
  immediately 
  shows 
  the 
  

   blue 
  color. 
  In 
  this 
  case 
  the 
  oscillator 
  consisted 
  of 
  two 
  zinc 
  

   plates 
  about 
  40 
  cm 
  square 
  with 
  a 
  spark 
  gap 
  between 
  them. 
  The 
  

   capacity 
  and 
  impedance 
  of 
  the 
  circuit 
  was 
  extremely 
  small. 
  

  

  The 
  unusual 
  sensitiveness 
  of 
  an 
  argon 
  tube 
  to 
  oscillatory 
  

   discharges 
  leads 
  us 
  to 
  believe 
  that 
  it 
  will 
  be 
  of 
  great 
  use 
  in 
  the 
  

   study 
  of 
  wave 
  motions 
  of 
  electricity. 
  As 
  we 
  have 
  seen, 
  it 
  is 
  

   competent 
  to 
  show 
  when 
  the 
  Hertz 
  oscillator 
  is 
  working 
  prop- 
  

   erly, 
  that 
  is, 
  sending 
  forth 
  electrical 
  oscillations 
  and 
  not 
  unidi- 
  

  

  * 
  Ann. 
  der 
  Physik 
  und 
  Chemie, 
  1893, 
  vol. 
  xlviii, 
  549, 
  Ebert 
  and 
  B. 
  Wiedemann. 
  

  

  