﻿Properties 
  of 
  Newly 
  Prepared 
  Gases. 
  149 
  

  

  28. 
  In 
  this 
  case 
  of 
  direct 
  electrolysis 
  where 
  no 
  secondary 
  

   action 
  takes 
  place, 
  or 
  other 
  chemical 
  effects 
  at 
  the 
  electrode 
  

   considerations 
  of 
  polarization 
  would 
  lead 
  us 
  to 
  expect 
  that 
  

   gases 
  would 
  come 
  off 
  carrying 
  with 
  them 
  a 
  charge 
  of 
  the 
  

   same 
  sign 
  as 
  that 
  which 
  they 
  carry 
  in 
  the 
  electrolyte. 
  Thus 
  

   in 
  the 
  case 
  of 
  polarization 
  due 
  to 
  a 
  layer 
  of 
  hydrogen 
  with 
  

   a 
  positive 
  charge 
  surrounding 
  the 
  electrode, 
  it 
  is 
  conceivable 
  

   that, 
  when 
  the 
  evolution 
  of 
  hydrogen 
  takes 
  place, 
  some 
  of 
  

   the 
  gas 
  composing 
  this 
  layer 
  would 
  come 
  off 
  without 
  losing 
  

   its 
  charge. 
  

  

  29. 
  In 
  seeking 
  to 
  explain 
  the 
  changes 
  of 
  sign 
  that 
  occur, 
  

   as 
  in 
  the 
  case 
  of 
  the 
  hydrogen 
  evolved 
  from 
  hydrochloric 
  acid, 
  

   it 
  must 
  be 
  remembered 
  that, 
  once 
  the 
  gas 
  has 
  acquired 
  a 
  

   charge, 
  only 
  a 
  small 
  quantity 
  of 
  electricity 
  is 
  lost 
  by 
  bubbling 
  

   through 
  liquids, 
  so 
  that 
  causes 
  which 
  influence 
  the 
  sign 
  of 
  

   the 
  charge 
  should 
  most 
  naturally 
  be 
  sought 
  for 
  at 
  the 
  place 
  

   where 
  the 
  gas 
  is 
  being 
  evolved, 
  and 
  may 
  be 
  due 
  to 
  the 
  state 
  

   of 
  the 
  electrode 
  or 
  to 
  impurities 
  in 
  the 
  electrolyte 
  in 
  the 
  

   immediate 
  vicinity 
  of 
  the 
  electrode. 
  

  

  30. 
  There 
  are 
  some 
  well-known 
  phenomena 
  which 
  point 
  to 
  

   an 
  explanation 
  of 
  the 
  results 
  obtained 
  with 
  hydrochloric 
  acid, 
  

   namely, 
  the 
  electrification 
  of 
  gases 
  by 
  glowing 
  metals 
  

   (J. 
  J. 
  Thomson, 
  Phil. 
  Mag. 
  Dec. 
  1896). 
  The 
  typical 
  effects 
  

   of 
  this 
  kind 
  are, 
  the 
  positive 
  electrification 
  of 
  oxygen 
  when 
  

   a 
  metal 
  is 
  being 
  oxidized, 
  and 
  the 
  negative 
  electrification 
  of 
  

   hydrogen 
  when 
  blown 
  past 
  a 
  hot 
  oxidized 
  metal 
  ; 
  the 
  metal 
  

   in 
  the 
  former 
  case 
  uniting 
  more 
  readily 
  with 
  the 
  negative 
  

   oxygen 
  atoms, 
  and 
  the 
  oxygen 
  in 
  the 
  latter 
  uniting 
  more 
  

   readily 
  with 
  the 
  positive 
  hydrogen 
  atoms. 
  The 
  only 
  necessity 
  

   for 
  the 
  high 
  temperature 
  of 
  the 
  metal 
  is 
  to 
  break 
  up 
  some 
  of 
  

   the 
  molecules 
  of 
  the 
  gas 
  into 
  atoms, 
  but 
  in 
  the 
  cases 
  we 
  are 
  

   dealing 
  with 
  the 
  gases 
  at 
  the 
  electrode 
  are 
  already 
  in 
  the 
  

   atomic 
  state. 
  We 
  should 
  therefore 
  expect 
  somewhat 
  similar 
  

   effects 
  to 
  take 
  place 
  when 
  the 
  gases 
  which 
  are 
  evolved 
  can 
  

   form 
  chemical 
  compounds 
  with 
  the 
  electrode, 
  or 
  with 
  bodies 
  

   either 
  dissolved 
  in 
  it 
  or 
  in 
  its 
  immediate 
  vicinity. 
  

  

  31. 
  If 
  the 
  above 
  principles 
  are 
  applied 
  to 
  the 
  case 
  of 
  

   hydrochloric 
  acid, 
  we 
  should 
  expect 
  when 
  the 
  gases 
  are 
  

   evolved 
  by 
  electrolysis, 
  that 
  the 
  hydrogen 
  would 
  carry 
  a 
  

   positive 
  charge, 
  and 
  the 
  chlorine 
  a 
  negative 
  charge. 
  The 
  

   subsequent 
  change 
  from 
  positive 
  to 
  negative, 
  in 
  the 
  case 
  of 
  

   the 
  hydrogen, 
  can 
  be 
  explained 
  by 
  supposing 
  a 
  small 
  quantity 
  

   of 
  hydrochloric 
  acid 
  to 
  be 
  formed 
  at 
  the 
  negative 
  electrode, 
  

   due 
  to 
  the 
  action 
  of 
  the 
  nascent 
  hydrogen 
  on 
  the 
  chlorine, 
  

   and 
  that 
  the 
  positive 
  hydrogen 
  atom 
  is 
  more 
  active 
  in 
  forming 
  

   a 
  compound 
  with 
  chlorine 
  than 
  the 
  negative. 
  A 
  similar 
  

  

  