﻿338 
  Trowbridge 
  and 
  Richards 
  — 
  Temperature 
  and 
  

  

  visible 
  lines 
  gradually 
  increases 
  in 
  brilliancy 
  with 
  the 
  gradual 
  

   fading 
  of 
  the 
  many-lined 
  spectrum 
  of 
  the 
  lower 
  temperatures 
  

   as 
  the 
  current 
  is 
  increased 
  ; 
  and 
  only 
  when 
  the 
  current 
  strength 
  

   becomes 
  very 
  great 
  do 
  the 
  extra 
  lines 
  disappear. 
  In 
  other 
  

   words, 
  the 
  change 
  from 
  one 
  condition 
  to 
  the 
  other 
  is 
  gradual. 
  

   In 
  the 
  case 
  of 
  nitrogen, 
  on 
  the 
  other 
  hand, 
  the 
  change 
  is 
  

   abrupt; 
  and 
  often 
  when 
  the 
  gas 
  is 
  near 
  its 
  sensitive 
  point 
  some 
  

   sparks 
  will 
  go 
  through 
  with 
  little 
  opposition, 
  while 
  others 
  give 
  

   the 
  banded 
  spectrum 
  and 
  the 
  non-oscillatory 
  photograph, 
  show- 
  

   ing 
  that 
  the 
  resistance 
  was 
  large. 
  Argon 
  is 
  like 
  nitrogen 
  in 
  

   the 
  suddeness 
  of 
  the 
  transition, 
  but 
  its 
  transition 
  takes 
  place 
  

   with 
  much 
  weaker 
  currents 
  than 
  with 
  . 
  either 
  hydrogen 
  or 
  

   nitrogen. 
  We 
  have 
  repeatedly 
  found 
  argon 
  to 
  give 
  the 
  pure 
  

   blue 
  spectrum 
  under 
  the 
  influence 
  of 
  the 
  discharge 
  of 
  the 
  full 
  

   battery 
  with 
  very 
  little 
  resistance 
  in 
  the 
  circuit 
  without 
  any 
  

   condenser, 
  or 
  with 
  less 
  than 
  eight 
  amperes; 
  for 
  the 
  resistance 
  

   of 
  each 
  cell 
  of 
  the 
  battery 
  is 
  about 
  the 
  quarter 
  of 
  an 
  ohm. 
  

  

  One 
  of 
  the 
  great 
  difficulties 
  of 
  investigating 
  the 
  intermediate 
  

   part 
  of 
  the 
  curve 
  lies 
  in 
  the 
  fact 
  that 
  no 
  tube 
  is 
  strong 
  enough 
  

   to 
  stand 
  the 
  continuous 
  application 
  of 
  temperatures 
  as 
  high 
  as 
  

   those 
  developed 
  by 
  the 
  corresponding 
  current. 
  On 
  the 
  other 
  

   hand, 
  the 
  repeated 
  instantaneous 
  discharge, 
  which 
  the 
  tube 
  will 
  

   stand, 
  cannot 
  be 
  estimated 
  when 
  the 
  resistance 
  rises 
  above 
  the 
  

   very 
  small 
  amount 
  necessary 
  to 
  damp 
  out 
  the 
  oscillations. 
  

  

  The 
  question 
  whether 
  the 
  change 
  in 
  the 
  spectrum 
  upon 
  

   increasing 
  the 
  current, 
  is 
  due 
  to 
  greater 
  heat 
  or 
  to 
  the 
  oscilla- 
  

   tory 
  motion, 
  is 
  one 
  which 
  is 
  not 
  easily 
  settled, 
  because 
  the 
  last 
  

   trace 
  of 
  the 
  return 
  oscillation 
  requires 
  hundreds 
  of 
  ohms 
  for 
  

   its 
  damping; 
  and 
  under 
  these 
  conditions 
  this 
  oscillation 
  is 
  not 
  

   easily 
  photographed. 
  The 
  fact 
  that 
  argon 
  offers 
  no 
  less 
  resist- 
  

   ance 
  than 
  hydrogen 
  or 
  nitrogen 
  to 
  electric 
  oscillations, 
  but 
  

   nevertheless 
  is 
  much 
  more 
  sensitive 
  to 
  increased 
  current, 
  tends 
  

   to 
  show 
  that 
  the 
  important 
  factor 
  in 
  the 
  question 
  is 
  not 
  the 
  

   oscillatory 
  nature 
  of 
  the 
  discharge, 
  but 
  only 
  the 
  great 
  quantity 
  

   which 
  is 
  always 
  attendant 
  upon 
  oscillatory 
  discharges. 
  

  

  Since 
  gases 
  do 
  not 
  strictly 
  follow 
  Ohms 
  law, 
  we 
  cannot 
  

  

  assume 
  that 
  the 
  formula 
  R= 
  j/_ 
  in 
  which 
  B, 
  is 
  resistance, 
  

  

  G 
  

  

  L=self 
  induction, 
  and 
  <?=capacity, 
  and 
  which 
  gives 
  the 
  limit- 
  

   ing 
  value 
  of 
  R 
  for 
  non-oscillatory 
  discharges, 
  rigidly 
  holds. 
  

   If, 
  however, 
  we 
  obtain 
  a 
  white 
  glow 
  in 
  hydrogen 
  gas 
  due 
  to 
  

   the 
  unidirectional 
  discharge 
  of 
  a 
  large 
  condenser 
  through 
  a 
  large 
  

   outside 
  resistance 
  and 
  then 
  proceed 
  to 
  increase 
  the 
  electro- 
  

   motive 
  force, 
  and 
  consequently 
  the 
  strength 
  of 
  the 
  current 
  in 
  

   our 
  unidirectional 
  discharge, 
  we 
  can 
  determine 
  whether 
  this 
  

   form 
  of 
  discharge 
  is 
  competent 
  to 
  produce 
  the 
  red 
  glow 
  in 
  

   hydrogen. 
  The 
  apparatus 
  which 
  was 
  used 
  for 
  this 
  purpose 
  

  

  