﻿Decomposition 
  of 
  Hydrogen 
  Peroxide 
  by 
  Light. 
  51 
  

  

  Experiments 
  on 
  the 
  Action 
  of 
  Light 
  on 
  H 
  2 
  2 
  Solutions 
  : 
  — 
  

  

  April 
  1.— 
  25 
  c.c. 
  H 
  2 
  0, 
  ["20-vol. 
  puriss."] 
  diluted 
  to 
  250 
  c.c. 
  

  

  100 
  c.c. 
  of 
  this 
  solution 
  exposed 
  to 
  sunshine 
  in 
  a 
  dish 
  from 
  

  

  8 
  a.m. 
  to 
  4 
  p.m. 
  On 
  April 
  2, 
  50 
  c.c. 
  water 
  added 
  and 
  dish 
  

  

  exposed 
  from 
  9 
  a.m. 
  to 
  5 
  p.m. 
  

  

  100 
  c.c. 
  of 
  same 
  solution 
  kept 
  in 
  dish 
  in 
  laboratory. 
  

  

  The 
  contents 
  of 
  the 
  dishes, 
  on 
  analysis 
  with 
  KMn0 
  4 
  , 
  showed 
  that 
  

  

  the 
  ratio 
  of 
  H 
  o 
  2 
  in 
  unexposed 
  dish 
  to 
  that 
  iu 
  the 
  exposed 
  dish 
  was 
  

  

  415 
  : 
  288. 
  

  

  April 
  4.— 
  10 
  c.c. 
  H. 
  2 
  2 
  diluted 
  to 
  250 
  c.c. 
  

  

  100 
  c.c. 
  of 
  this 
  exposed 
  on 
  April 
  4 
  and 
  5 
  to 
  sunshine. 
  

   100 
  c.c. 
  of 
  this 
  in 
  dish 
  in 
  laboratory. 
  

   The 
  temperature 
  of 
  the 
  solutions 
  in 
  each 
  constantly 
  observed 
  ; 
  in 
  

   some 
  cases 
  temperature 
  of 
  exposed 
  dish 
  lower 
  than 
  other. 
  Extreme 
  

   variations 
  not 
  more 
  than 
  3 
  degrees. 
  Average 
  temperature 
  did 
  

   not 
  differ 
  by 
  more 
  than 
  a 
  degree. 
  

  

  Analysis 
  of 
  contents 
  showed 
  ratio 
  of 
  H 
  2 
  2 
  in 
  unexposed 
  dish 
  to 
  

   H 
  2 
  2 
  in 
  exposed 
  dish 
  ^59 
  : 
  125 
  

  

  April 
  9.— 
  10 
  c.c. 
  H 
  2 
  2 
  diluted 
  to 
  250 
  c.c. 
  

  

  100 
  c.c. 
  exposed 
  in 
  dish 
  April 
  9, 
  8 
  a.m. 
  to 
  3.40 
  p.m. 
  April 
  1 
  0, 
  

  

  7.45 
  a.m. 
  to 
  6 
  p.m. 
  25 
  c.c. 
  water 
  being 
  added. 
  

   100 
  c.c. 
  in 
  dish 
  in 
  laboratory 
  in 
  large 
  water-bath 
  kept 
  at 
  a 
  

   temperature 
  2-5 
  degrees 
  higher 
  than 
  the 
  exposed 
  dish. 
  

   H.,0 
  2 
  in 
  unexposed 
  but 
  warmed 
  dish 
  : 
  H 
  2 
  2 
  in 
  exposed 
  dish 
  

  

  159 
  : 
  121. 
  

  

  April 
  12 
  to 
  April 
  16. 
  — 
  A 
  similar 
  experiment 
  to 
  the 
  last 
  one 
  gave 
  

  

  144 
  : 
  121. 
  

  

  June 
  16. 
  — 
  40 
  c.c. 
  H 
  2 
  2 
  [" 
  20-vol. 
  puriss.," 
  but 
  containing 
  free 
  

   H.,S0 
  4 
  , 
  namely 
  '000011 
  grm. 
  acid 
  hydrogen 
  per 
  litre] 
  

   diluted 
  to 
  1000 
  c.c. 
  

  

  (a) 
  100 
  c.c. 
  of 
  this 
  diluted 
  with 
  another 
  100 
  c.c. 
  of 
  water 
  and 
  

  

  exposed 
  in 
  dish 
  to 
  available 
  sunshine 
  between 
  June 
  

   16 
  — 
  June 
  20, 
  but 
  kept 
  diluted 
  by 
  successive 
  additions 
  

   of 
  water. 
  

  

  (b) 
  100 
  c.c. 
  of 
  this 
  solution 
  exposed 
  between 
  June 
  16 
  — 
  June 
  

  

  20 
  as 
  above, 
  but 
  without 
  dilution. 
  

  

  (c) 
  100 
  c.c. 
  of 
  this 
  in 
  dish, 
  covered 
  with 
  a 
  thin 
  glass 
  plate, 
  

  

  but 
  exposed 
  to 
  sunshine, 
  June 
  16 
  — 
  June 
  20, 
  as 
  above, 
  

   (c?) 
  100 
  c.c. 
  of 
  this 
  put 
  in 
  a 
  basin 
  in 
  desiccator 
  over 
  strong 
  

   sulphuric 
  acid 
  and 
  kept 
  in 
  the 
  dark 
  June 
  16 
  — 
  July 
  15, 
  

   when 
  its 
  volume 
  was 
  found 
  to 
  be 
  62 
  c.c. 
  

   H 
  2 
  o 
  in 
  100 
  c.c. 
  of 
  this 
  solution 
  : 
  HA, 
  in 
  (a) 
  : 
  H,0 
  

   in 
  (6) 
  : 
  H 
  2 
  2 
  in 
  (c) 
  : 
  H 
  2 
  2 
  in 
  (d) 
  :— 
  

   164 
  : 
  85 
  : 
  77 
  : 
  103 
  : 
  142. 
  

  

  E 
  2 
  

  

  