﻿1875.] 
  Hydrogen 
  and 
  Acids 
  on 
  Iron 
  and 
  Steel. 
  177 
  

  

  ing-strain 
  of 
  the 
  same, 
  after 
  being 
  5 
  days 
  on 
  a 
  hot 
  plate 
  to 
  expel 
  the 
  hy- 
  

   drogen, 
  is 
  as 
  follows 
  : 
  — 
  

  

  

  Break- 
  

   ing- 
  

   strain. 
  

  

  Mean 
  error 
  

   in 
  breaking- 
  

   strain. 
  

  

  Elongation 
  of 
  

   length 
  tested. 
  

  

  Mean 
  error 
  

   in 
  

  

  elongation. 
  

  

  Number 
  of 
  

   experiments 
  

   for 
  each 
  result 
  

   given. 
  

  

  Charcoal-iron 
  wire 
  con- 
  "1 
  

   taining 
  H 
  occluded 
  in 
  \- 
  

   IPSO* 
  J 
  

  

  Charcoal-iron 
  wire, 
  H 
  1 
  

  

  Charcoal-iron 
  wire 
  con- 
  ] 
  

   taining 
  H 
  occluded 
  in 
  I 
  

  

  Charcoal-iron 
  wire, 
  H 
  1 
  

  

  100 
  

   106-62 
  

   100 
  

   105-35 
  

  

  per 
  cent. 
  

   ±1-33 
  

  

  ±7-10 
  

  

  ±0-3 
  

  

  ±1-1 
  

  

  per 
  cent. 
  

   1-3 
  

  

  4 
  

  

  1-41 
  

   4-6 
  

  

  per 
  cent. 
  

   ±0-23 
  

  

  ±0-33 
  

  

  +0-41 
  

  

  ±0-33 
  

  

  6 
  

   6 
  

   6 
  

   6 
  

  

  The 
  diminution 
  of 
  elongation 
  and 
  breaking-strain 
  caused 
  by 
  occlusion 
  

   of 
  hydrogen 
  is 
  very 
  marked 
  in 
  these 
  experiments, 
  but 
  is 
  quite 
  equalled 
  

   by 
  the 
  following 
  experiments 
  on 
  mild 
  steel 
  containing 
  about 
  0*227 
  percent, 
  

   carbon. 
  The 
  wires 
  were 
  allowed 
  to 
  remain 
  in 
  very 
  dilute 
  hydrochloric 
  acid 
  

   about 
  5 
  hours, 
  then, 
  when 
  tested, 
  heated 
  to 
  about 
  100° 
  C. 
  for 
  12 
  hours, 
  by 
  

   which 
  means 
  a 
  portion 
  of 
  the 
  occluded 
  H 
  was 
  expelled. 
  

  

  

  Break- 
  

   ing- 
  

   strain. 
  

  

  Mean 
  error 
  

   in 
  breaking- 
  

   strain. 
  

  

  Elongation. 
  

  

  Mean 
  error 
  

   in 
  

  

  elongation. 
  

  

  Number 
  of 
  

   experiments 
  

  

  for 
  each 
  

   result 
  given. 
  

  

  Annealed 
  mild 
  steel 
  1 
  

  

  Annealed 
  mild 
  steel, 
  H 
  "] 
  

   partially 
  expelled 
  by 
  > 
  

  

  Bright 
  mild 
  steel 
  be- 
  ] 
  

   fore 
  immersion 
  in 
  \ 
  

   HC1 
  J 
  

  

  Bright 
  mild 
  steel 
  con- 
  \ 
  

  

  Bright 
  mild 
  steel 
  H 
  1 
  

   partially 
  expelled 
  by 
  L 
  

  

  Bright 
  mild 
  steel, 
  H 
  1 
  

   completely 
  expelled 
  > 
  

   by 
  heating 
  7 
  days 
  ... 
  J 
  

  

  100 
  

   104-77 
  

  

  104-03 
  

  

  100 
  

  

  108-68 
  

  

  114-29 
  

  

  per 
  cent. 
  

   + 
  5-08 
  

  

  ± 
  3-81 
  

  

  ±10-1 
  

   ± 
  9-2 
  

   ± 
  1-5 
  

  

  ± 
  8-4 
  

  

  per 
  cent. 
  

   20-1 
  

  

  15-4 
  

  

  1- 
  66 
  

  

  2- 
  8 
  

   216 
  

  

  3- 
  42 
  

  

  per 
  cent. 
  

   ±061 
  

  

  ±1-2 
  

  

  ±044 
  

   ±046 
  

   ±0-38 
  

  

  ±0-75 
  

  

  9 
  

   9 
  

  

  6 
  

   6 
  

   6 
  

  

  6 
  

  

  These 
  experiments 
  show 
  : 
  — 
  

  

  1st. 
  That 
  the 
  tensile 
  strain 
  of 
  steel 
  is 
  o^minished 
  by 
  the 
  occlusion 
  of 
  

   hydrogen, 
  and 
  that 
  as 
  the 
  hydrogen 
  is 
  expelled 
  (a 
  process 
  of 
  long 
  duration) 
  

  

  