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  Mr. 
  H. 
  E. 
  Watson 
  on 
  some 
  

  

  And 
  the 
  following 
  to 
  both 
  hydrogen 
  peroxide 
  and 
  

   sunlight 
  : 
  — 
  

  

  ♦Yellow 
  Ochre. 
  

  

  Other 
  Ochres. 
  

   ♦Raw 
  Sienna. 
  

  

  Orange 
  Chrome. 
  

  

  Red 
  Lead. 
  

  

  Light 
  Red. 
  

   ♦Venetian 
  Red. 
  

   *Burnt 
  Sienna. 
  

   *Indian 
  Red. 
  

  

  Madder 
  Red. 
  

  

  Raw 
  Umber 
  ? 
  

  

  Bistre 
  ? 
  

  

  Burnt 
  Umber. 
  

   ♦Terra 
  Verte. 
  

  

  Cobalt 
  Green. 
  

   ♦Chromium 
  Oxide. 
  

  

  Transparent 
  Chromium 
  Oxide. 
  

  

  Smalt. 
  

   ♦Cobalt 
  Blue. 
  

  

  Ceruleum. 
  

   ♦Prussian 
  Blue. 
  

   ♦Antwerp 
  Blue. 
  

  

  * 
  Paints 
  marked 
  with 
  a 
  star 
  were 
  treated 
  with 
  ozone, 
  and 
  remained 
  

   unaffected. 
  

  

  The 
  most 
  striking 
  fact 
  in 
  connexion 
  with 
  the 
  above 
  tables 
  

   is 
  the 
  practically 
  identical 
  action 
  of 
  hydrogen 
  peroxide 
  and 
  

   ozone. 
  Indigo 
  appears 
  to 
  be 
  the 
  only 
  exception, 
  being 
  quite 
  

   stable 
  towards 
  the 
  former 
  reagent, 
  but 
  easily 
  bleached 
  by 
  

   the 
  latter. 
  This 
  similarity 
  of 
  action, 
  however, 
  is 
  precisely 
  

   what 
  would 
  be 
  expected 
  from 
  the 
  chemical 
  nature 
  of 
  the 
  

   reagents, 
  and, 
  indeed, 
  it 
  seems 
  rather 
  strange 
  that 
  the 
  relative 
  

   times 
  taken 
  to 
  complete 
  the 
  reaction 
  are 
  not 
  more 
  comparable. 
  

   The 
  explanation 
  of 
  this 
  is 
  probably 
  to 
  be 
  found 
  in 
  the 
  fact 
  

   that 
  in 
  neither 
  case 
  were 
  the 
  experiments 
  carried 
  out 
  quan- 
  

   titatively, 
  the 
  weights 
  of 
  paint 
  and 
  bleaching 
  agent 
  being 
  

   only 
  of 
  the 
  same 
  order 
  of 
  magnitude 
  in 
  each 
  set 
  of 
  experi- 
  

   ments. 
  Too 
  much 
  attention 
  must 
  not 
  therefore 
  be 
  paid 
  to 
  

   the 
  actual 
  times 
  taken. 
  

  

  Bearing 
  this 
  fact 
  in 
  mind, 
  it 
  will 
  be 
  seen 
  that 
  in 
  the 
  

   majority 
  of 
  cases 
  the 
  action 
  of 
  these 
  oxidizing 
  agents 
  and 
  of 
  

   light 
  is 
  the 
  same, 
  and 
  this 
  appears 
  to 
  be 
  fairly 
  strong, 
  though 
  

   of 
  course 
  not 
  conclusive 
  evidence, 
  that 
  in 
  general, 
  the 
  fading 
  

   of 
  paints 
  is 
  due 
  to 
  oxidation. 
  With 
  regard 
  to 
  the 
  actual 
  

   active 
  agent, 
  it 
  may 
  be 
  again 
  mentioned 
  that 
  hydrogen 
  

   peroxide 
  is 
  known 
  to 
  form 
  from 
  moist 
  air 
  in 
  presence 
  of 
  

   organic 
  matter 
  and 
  light, 
  while 
  the 
  production 
  of 
  ozone 
  

   under 
  these 
  circumstances 
  is 
  not 
  certain. 
  Moreover, 
  it 
  was 
  

   found 
  that 
  dry 
  ozone 
  was 
  without 
  bleaching 
  action, 
  and 
  con- 
  

   sequently 
  the 
  action 
  may 
  be 
  due 
  to 
  the 
  intermediate 
  formation 
  

   of 
  hydrogen 
  peroxide 
  in 
  presence 
  of 
  water. 
  

  

  There 
  is 
  one 
  more 
  point 
  of 
  interest. 
  The 
  report 
  of 
  1888 
  

   mentions 
  Antwerp 
  Blue 
  and 
  Prussian 
  Blue 
  as 
  being 
  two 
  of 
  

   the 
  most 
  fugitive 
  colours, 
  a 
  fact 
  well 
  known 
  to 
  artists. 
  

   However, 
  it 
  will 
  be 
  seen 
  that 
  neither 
  is 
  attacked 
  by 
  hydrogen 
  

  

  