﻿472 
  Mr. 
  L. 
  Yegard 
  on 
  the 
  Electric 
  Discharge 
  

  

  reversible. 
  In 
  both 
  cases 
  the 
  characteristic 
  curve 
  gets 
  a 
  

   permanent 
  change 
  and 
  the 
  interval 
  for 
  uniform 
  discharge 
  is 
  

   reduced 
  to 
  such 
  a 
  degree 
  that 
  generally 
  this 
  type 
  is 
  obtained 
  

   only 
  for 
  the 
  very 
  smallest 
  currents 
  that 
  can 
  be 
  made 
  to 
  pass. 
  

   A 
  tube 
  giving 
  a 
  striated 
  or 
  dark 
  column 
  when 
  left 
  to 
  itself 
  

   has 
  a 
  tendency 
  to 
  recover 
  or 
  to 
  increase 
  the 
  interval 
  of 
  

   uniform 
  discharge. 
  This 
  will 
  make 
  the 
  characteristic 
  curve 
  

   change 
  with 
  time. 
  The 
  recovery 
  of 
  a 
  tube 
  brought 
  into 
  the 
  

   state 
  of 
  dark 
  column 
  was 
  also 
  observed 
  by 
  Skinner 
  for 
  

   nitrogen. 
  

  

  Fig. 
  5 
  (PI. 
  XIV.) 
  shows 
  how 
  the 
  characteristic 
  curve 
  was 
  

   changed 
  when 
  the 
  discharge 
  was 
  brought 
  from 
  the 
  uniform 
  

   to 
  the 
  striated 
  state. 
  

  

  The 
  reversibility 
  of 
  the 
  uniform 
  discharge 
  is 
  a 
  very 
  impor- 
  

   tant 
  point 
  in 
  connexion 
  with 
  the 
  discharge 
  through 
  HCl, 
  for 
  

   it 
  shows 
  that 
  at 
  least 
  within 
  these 
  limits 
  the 
  conditions 
  

   for 
  discharge 
  are 
  not 
  altered 
  by 
  the 
  current 
  through 
  it 
  to 
  

   such 
  an 
  amount 
  as 
  to 
  give 
  any 
  appreciable 
  change 
  in 
  the 
  

   distribution 
  of 
  potential. 
  As 
  a 
  possible 
  decomposition 
  

   necessarily 
  would 
  be 
  accompanied 
  by 
  a 
  change 
  in 
  the 
  

   character 
  of 
  discharge 
  the 
  reversibility 
  shows 
  that 
  the 
  

   medsuredl 
  uniform 
  discharge 
  corresponds 
  to 
  the 
  undecomposed 
  

   liyd 
  roclddrie 
  ^ 
  acid 
  ■gas 
  . 
  

  

  {^'\ 
  * 
  i 
  • 
  . 
  " 
  < 
  < 
  ' 
  Djis^oharge 
  through 
  HBr. 
  

  

  § 
  8. 
  The 
  luminosity 
  in 
  the 
  positive 
  column 
  compared 
  for 
  

   ^'4iigi 
  c.i5ri';ents. 
  was 
  much 
  weaker 
  in 
  HBr 
  than 
  in 
  HCl 
  and 
  

   showed 
  a 
  darker 
  blue 
  colour. 
  The 
  discharge 
  could 
  be 
  kept 
  

   perfectly 
  steady 
  and 
  the 
  interval 
  of 
  stability 
  for 
  the 
  uniform 
  

   column 
  proved 
  to 
  be 
  much 
  greater 
  than 
  for 
  HCl, 
  and 
  as 
  a 
  

   matter 
  of 
  fact 
  within 
  the 
  current 
  limits 
  that 
  could 
  be 
  got 
  by 
  

   using 
  the 
  lowest 
  resistance 
  and 
  largest 
  voltage 
  at 
  hand 
  the 
  

   striated 
  state 
  was 
  not 
  obtained, 
  and 
  as 
  the 
  measurements 
  

   in 
  a 
  uniform 
  column 
  were 
  my 
  chief 
  object 
  no 
  further 
  

   effort 
  was 
  made 
  to 
  obtain 
  possible 
  limits 
  for 
  the 
  uniform 
  

   discharge. 
  

  

  If 
  there 
  was 
  no 
  change 
  of 
  pressure 
  the 
  conditions 
  were 
  

   found 
  to 
  be 
  reversible 
  with 
  regard 
  to 
  current, 
  which 
  shows 
  

   that 
  no 
  decomposition 
  took 
  place 
  which 
  was 
  able 
  to 
  cause 
  

   any 
  appreciable 
  influence 
  on 
  the 
  discharge. 
  

  

  In 
  Table 
  III. 
  is 
  given 
  the 
  distribution 
  of 
  potential 
  in 
  HBr 
  

   for 
  a 
  series 
  of 
  pressures. 
  It 
  contains 
  at 
  each 
  pressure 
  the 
  

   measurements 
  corresponding 
  to 
  smallest 
  and 
  largest 
  current 
  

   for 
  which 
  observations 
  are 
  taken. 
  

  

  