﻿1875.] 
  

  

  Hydrogen 
  and 
  Acids 
  on 
  Iron 
  and 
  Steel. 
  

  

  179 
  

  

  Professor 
  Stewart 
  kindly 
  allowed 
  me 
  the 
  use 
  of 
  the 
  Owens 
  College 
  

   apparatus, 
  with 
  which 
  soni3 
  of 
  the 
  following 
  results 
  were 
  obtained 
  : 
  — 
  

  

  Kesistance 
  of 
  6 
  feet 
  bright 
  charcoal-iron 
  wire 
  = 
  100 
  100 
  

  

  Eesistance 
  of 
  6 
  feet 
  bright 
  charcoal-iron 
  wire 
  after 
  5 
  hours 
  in 
  dilute 
  H 
  2 
  S0 
  4 
  = 
  

  

  107'14, 
  or, 
  allowing 
  for 
  iron 
  eaten 
  away 
  by 
  acid 
  105*6 
  

  

  Eesistance 
  of 
  6 
  feet 
  bright 
  charcoal-iron 
  wire 
  after 
  5 
  hours 
  in 
  dilute 
  HC1= 
  

  

  114-3, 
  or, 
  allowing 
  for 
  iron 
  eaten 
  away 
  by 
  acid 
  109*4 
  

  

  The 
  wires 
  were 
  somewhat 
  eaten 
  away 
  by 
  the 
  acid, 
  so 
  allowance 
  had 
  to 
  

   be 
  made 
  for 
  the 
  increased 
  resistance 
  due 
  to 
  decreased 
  sectional 
  area 
  ; 
  this 
  

   is 
  made 
  in 
  the 
  column 
  to 
  the 
  right. 
  

  

  About 
  50 
  feet 
  of 
  hard 
  bright 
  iron 
  wire, 
  after 
  24 
  hours' 
  immersion 
  in 
  

   dilute 
  sulphuric 
  acid, 
  gave 
  a 
  resistance 
  of 
  2-94 
  ohms, 
  and 
  2*92 
  ohms 
  after 
  

   the 
  occluded 
  hydrogen 
  had 
  been 
  expelled 
  by 
  heat. 
  

  

  The 
  above 
  results, 
  though 
  far 
  from 
  uniform, 
  are 
  sufficient 
  to 
  show 
  that 
  

   there 
  is 
  an 
  increase 
  in 
  the 
  resistance 
  of 
  iron 
  wire 
  when 
  it 
  contains 
  

   occluded 
  hydrogen. 
  I 
  hope 
  soon 
  to 
  make 
  further 
  experiments 
  on 
  this 
  

   subject. 
  It 
  is 
  worthy 
  of 
  remark 
  that 
  Professor 
  Graham 
  found 
  the 
  resist- 
  

   ance 
  of 
  palladium 
  containing 
  occluded 
  hydrogen 
  was 
  increased 
  about 
  

   25 
  per 
  cent. 
  He 
  also 
  discovered 
  that 
  a 
  palladium 
  wire 
  first 
  elongated 
  

   when 
  charged 
  with 
  hydrogen, 
  and 
  then 
  contracted 
  when 
  the 
  hydrogen 
  

   was 
  withdrawn 
  to 
  less 
  than 
  its 
  original 
  length. 
  The 
  writer 
  has 
  detected 
  

   a 
  very 
  small 
  and 
  similar 
  change 
  in 
  the 
  length 
  of 
  annealed 
  iron 
  wire 
  

   under 
  like 
  condition, 
  but 
  has 
  not 
  yet 
  observed 
  it 
  in 
  bright 
  iron 
  wire, 
  

   though 
  he 
  does 
  not 
  despair 
  of 
  doing 
  so. 
  

  

  Diffusion 
  of 
  Hydrogen. 
  

  

  A 
  number 
  of 
  experiments 
  were 
  made 
  by 
  allowing 
  one 
  half 
  of 
  a 
  piece 
  

   of 
  bright 
  iron 
  or 
  steel 
  wire 
  to 
  be 
  acted 
  on 
  by 
  dilute 
  acid, 
  and 
  thus 
  to 
  

   occlude 
  hydrogen 
  while 
  the 
  other 
  half 
  was 
  protected 
  from 
  this 
  action, 
  

   with 
  a 
  view 
  of 
  ascertaining 
  if 
  the 
  occluded 
  hydrogen 
  could 
  spread 
  along 
  

   the 
  interior 
  of 
  the 
  iron. 
  Great 
  difference 
  was 
  observed 
  in 
  the 
  behaviour 
  

   of 
  iron 
  and 
  steel 
  ; 
  the 
  fibrous 
  structure 
  of 
  iron 
  wire 
  allows 
  the 
  hydrogen 
  

   occluded 
  in 
  the 
  part 
  acted 
  on 
  by 
  acid 
  to 
  spread 
  into 
  the 
  other 
  part, 
  di- 
  

   stinct 
  traces 
  of 
  hydrogen 
  being 
  observed 
  17 
  centims. 
  from 
  the 
  part 
  affected 
  

   by 
  acid. 
  The 
  close 
  unfibrous 
  structure 
  of 
  steel, 
  on 
  the 
  contrary, 
  seems 
  to 
  

   oppose 
  this 
  altogether, 
  it 
  being 
  questionable 
  if 
  the 
  hydrogen 
  spreads 
  2 
  to 
  

   3 
  centims. 
  beyond 
  the 
  part 
  immersed 
  in 
  acid. 
  

  

  When 
  that 
  part 
  of 
  the 
  iron 
  wire 
  which 
  was 
  protected 
  from 
  but 
  still 
  

   affected 
  by 
  the 
  acid 
  was 
  broken 
  and 
  the 
  fracture 
  moistened, 
  the 
  bubbles 
  

   of 
  gas 
  arose 
  almost 
  exclusively 
  from 
  the 
  centre 
  of 
  the 
  fracture, 
  while 
  

   from 
  the 
  part 
  immersed 
  in 
  acid 
  they 
  arose 
  equally 
  from 
  the 
  whole 
  sur- 
  

   face, 
  and 
  took 
  less 
  time 
  to 
  attain 
  their 
  maximum. 
  

  

  