﻿726 
  

  

  Mr. 
  H. 
  E. 
  Watson 
  on 
  some 
  

  

  be 
  at 
  once 
  seen. 
  Below 
  is 
  a 
  table 
  giving 
  the 
  results 
  for 
  a 
  

   number 
  of 
  paints. 
  In 
  addition, 
  under 
  the 
  heading 
  " 
  Sun- 
  

   light 
  " 
  is 
  given 
  the 
  effect 
  of 
  light 
  on 
  the 
  same 
  paints. 
  By 
  

   the 
  courtesy 
  of 
  a 
  well-known 
  firm 
  of 
  colour 
  manufacturers, 
  

   I 
  was 
  enabled 
  to 
  have 
  access 
  to 
  a 
  number 
  of 
  specimens 
  

   of 
  water-colours 
  which 
  had 
  been 
  as 
  far 
  as 
  possible 
  exposed 
  

   to 
  sunlight 
  for 
  30 
  years, 
  and 
  also 
  to 
  corresponding 
  specimens 
  

   which 
  had 
  been 
  kept 
  in 
  the 
  dark. 
  It 
  is 
  from 
  these 
  that 
  the 
  

   results 
  are 
  taken. 
  

  

  Since 
  writing 
  the 
  above, 
  a 
  paper 
  on 
  " 
  The 
  Action 
  of 
  

   Ozone 
  on 
  Water-colour 
  Pigments/'' 
  by 
  Sir 
  William 
  Abney, 
  

   has 
  appeared 
  *. 
  As 
  ozone 
  and 
  hydrogen 
  peroxide 
  are 
  both 
  

   powerful 
  oxidizing 
  agents, 
  a 
  comparison 
  of 
  the 
  effects 
  pro- 
  

   duced 
  by 
  them 
  should 
  prove 
  interesting, 
  and 
  consequently 
  

   the 
  results 
  in 
  the 
  above-mentioned 
  paper 
  are 
  included 
  in 
  the 
  

   following 
  tables 
  under 
  the 
  heading 
  " 
  Ozone/' 
  The 
  figures 
  

   show 
  the 
  time 
  taken 
  by 
  moist 
  ozonized 
  air 
  to 
  bleach 
  the 
  

   paint. 
  

  

  Name 
  of 
  Point. 
  

  

  Sunlight. 
  

  

  H 
  2 
  2 
  . 
  

  

  a. 
  

  

  -one. 
  

  

  Naples 
  Yellow 
  

  

  Lemon 
  Yellow 
  

  

  King's 
  Yellow 
  

  

  Strontium 
  Yellow 
  . 
  . 
  

  

  Gamboge 
  

  

  Indian 
  Yellow 
  

  

  Yellow 
  Lake 
  

  

  No 
  change. 
  

  

  No 
  change. 
  

  

  Quite 
  faded. 
  

  

  No 
  change. 
  

  

  Browned. 
  

  

  Browned. 
  

  

  Quite 
  faded. 
  

  

  Browned. 
  

  

  Slightly 
  green. 
  

  

  Dark 
  brown. 
  

  

  Brown. 
  

  

  White. 
  

  

  White. 
  

  

  White. 
  

  

  Much 
  faded. 
  

  

  Darkened. 
  

  

  Greyish. 
  

  

  White. 
  

  

  White. 
  

  

  White. 
  

  

  Darkened. 
  

  

  Blue-grey. 
  

  

  Greenish. 
  

  

  White. 
  

  

  Deepened, 
  1 
  day. 
  

  

  White, 
  2 
  weeks. 
  

  

  Colourless 
  on 
  warming. 
  

  

  Brown 
  in 
  10 
  minutes. 
  

  

  Slight 
  change. 
  

  

  Colourless 
  in 
  1 
  day. 
  

  

  Colourless 
  in 
  3 
  days. 
  

  

  Dissolved 
  at 
  once. 
  

  

  Paled 
  slightly. 
  

  

  Stable. 
  

  

  Paler. 
  

  

  Colourless 
  in 
  2 
  weeks. 
  

  

  Colourless 
  on 
  heating 
  1 
  day. 
  

  

  Colourless 
  in 
  1 
  day. 
  

  

  Colourless 
  in 
  1 
  week. 
  

  

  Paler. 
  

  

  Colourless 
  in 
  1 
  day. 
  

  

  Colourless 
  in 
  1 
  day. 
  

  

  Colourless 
  on 
  heating 
  4 
  days. 
  

  

  Colourless 
  in 
  1 
  week. 
  

  

  Brown 
  at 
  once. 
  

  

  Colourless 
  in 
  1 
  day. 
  

  

  Brown 
  at 
  once. 
  

  

  Stable. 
  

  

  fa 
  

  

  

  

  

  

  4 
  

  

  4 
  

  

  Unci 
  

   Unci 
  

  

  

  

  

  

  4 
  

   

  

  2 
  

  

  1 
  

   

   

  

  

  

  m 
  

   45 
  

  

  50 
  

   

  

  

   anged. 
  

   anged. 
  

  

  30 
  

  

  10 
  

  

  

   20 
  

  

  10 
  

   15 
  

   50 
  

  

  45 
  

  

  40 
  

  

  Cadmium 
  Yellow 
  ... 
  

  

  Chrome 
  Yellow 
  

  

  Vermillion 
  

  

  Scarlet 
  Lake 
  

  

  Crimson 
  Lake 
  

  

  Purple 
  Lake 
  

  

  Carmine 
  

  

  Madder 
  Carmine 
  ... 
  

  

  Rose 
  Madder 
  

  

  Purple 
  Madder 
  

  

  Madder 
  Brown 
  

  

  Vandyke 
  Brown 
  ... 
  

   Sepia 
  

  

  Emerald 
  Green 
  

  

  Sap 
  Green 
  

  

  Blue 
  Verditer 
  

  

  Indigo 
  

  

  

  * 
  Proc. 
  Roy. 
  Soc, 
  A. 
  vol. 
  lxxx. 
  p. 
  146 
  (1908). 
  

  

  