﻿Decomposition 
  of 
  Hydrogen 
  Peroxide 
  by 
  Light, 
  45 
  

  

  the 
  ebonite 
  rod, 
  and 
  so 
  an 
  annular 
  air-space 
  of 
  about 
  3 
  mm. 
  

   was 
  left 
  surrounding 
  the 
  ebonite 
  rod 
  at 
  this 
  part. 
  The 
  small 
  

   ebonite 
  plate 
  k 
  could 
  be 
  pushed 
  down 
  when 
  the 
  apparatus 
  was 
  

   not 
  in 
  use 
  to 
  close 
  this 
  space, 
  and 
  so 
  to 
  exclude 
  dust 
  and 
  damp. 
  

  

  The 
  dish 
  used 
  in 
  the 
  experiments 
  described 
  was 
  a 
  guttapercha 
  

   photographic 
  dish, 
  measuring 
  about 
  10 
  cm. 
  by 
  12 
  cm. 
  The 
  

   wire 
  gauze 
  was 
  6 
  cm. 
  square. 
  Its 
  distance 
  from 
  the 
  surface 
  

   of 
  the 
  liquid 
  was 
  about 
  one 
  centimetre 
  in 
  the 
  earlier 
  experi- 
  

   ments, 
  about 
  *8 
  cm. 
  in 
  those 
  of 
  August 
  17 
  & 
  19. 
  Its 
  position 
  

   during 
  each 
  day 
  was 
  fixed 
  throughout 
  that 
  day. 
  

  

  In 
  making 
  an 
  experiment 
  a 
  definite 
  volume 
  of 
  water, 
  

   generally 
  75 
  c. 
  c, 
  was 
  placed 
  in 
  the 
  dish. 
  The 
  dish 
  and 
  the 
  

   quadrants 
  connected 
  with 
  it 
  were 
  electrified 
  by 
  touching 
  the 
  

   wire 
  s 
  (fig. 
  1) 
  with 
  a 
  wire 
  connected 
  to 
  the 
  negative 
  pole 
  of 
  a 
  

   water-battery 
  (the 
  positive 
  pole 
  being 
  earthed) 
  . 
  The 
  touching- 
  

   wire 
  was 
  removed, 
  leaving 
  the 
  dish 
  charged 
  — 
  the 
  deflexion 
  noted 
  

   (the 
  fourth 
  column 
  in 
  the 
  tables), 
  another 
  reading 
  taken 
  in 
  

   twenty 
  minutes' 
  time 
  (the 
  fifth 
  column 
  in 
  the 
  tables). 
  Many 
  

   preliminary 
  experiments 
  seemed 
  to 
  show 
  that 
  this 
  was 
  a 
  con- 
  

   venient 
  method 
  of 
  procedure, 
  especially 
  with 
  the 
  apparatus 
  

   available. 
  The 
  sensitiveness 
  of 
  the 
  electrometer 
  remained 
  

   sensibly 
  constant 
  for 
  several 
  days 
  in 
  these 
  experiments, 
  the 
  

   needle 
  requiring 
  only 
  a 
  small 
  charge. 
  A 
  convenient 
  deflexion 
  

   could 
  always 
  be 
  obtained 
  by 
  varying 
  the 
  number 
  of 
  cells 
  

   used 
  in 
  the 
  water-battery. 
  An 
  experiment 
  with 
  water 
  would 
  

   be 
  followed 
  generally 
  by 
  one 
  with 
  hydrogen 
  peroxide, 
  the 
  

   same 
  volume 
  of 
  this 
  being 
  used 
  and 
  all 
  the 
  arrangements 
  

   being 
  just 
  the 
  same; 
  or 
  sometimes 
  two 
  experiments 
  conse- 
  

   cutively 
  were 
  made 
  with 
  the 
  same 
  liquid. 
  

  

  The 
  difference 
  of 
  potential 
  between 
  the 
  liquid 
  and 
  the 
  wire 
  

   gauze 
  varied 
  from 
  20 
  to 
  30 
  volts. 
  The 
  sensitiveness 
  of 
  the 
  

   electrometer 
  was 
  found 
  approximately 
  by 
  using 
  a 
  Clark's 
  cell. 
  

  

  The 
  experiments 
  were 
  made 
  at 
  the 
  author's 
  house 
  at 
  

   Kessingland, 
  on 
  the 
  coast 
  of 
  Suffolk. 
  

  

  The 
  results 
  of 
  all 
  the 
  experiments 
  made 
  with 
  this 
  apparatus 
  

   between 
  August 
  8 
  and 
  August 
  19 
  are 
  given 
  in 
  the 
  Tables. 
  

   These 
  results 
  are 
  also 
  plotted. 
  An 
  ordinate 
  in 
  each 
  case 
  

   shows 
  the 
  loss 
  of 
  electrification 
  during 
  an 
  experiment, 
  as 
  

   given 
  by 
  the 
  sixth 
  column 
  of 
  the 
  tables, 
  made 
  at 
  the 
  time 
  of 
  

   day 
  given 
  by 
  the 
  abscissa. 
  The 
  experiments 
  with 
  water 
  are 
  

   indicated 
  thus 
  x 
  , 
  those 
  with 
  H 
  2 
  2 
  ®. 
  

  

  In 
  annotation 
  of 
  these 
  results, 
  it 
  may 
  be 
  remarked 
  that 
  

   those 
  on 
  August 
  8, 
  9, 
  11, 
  17 
  are 
  in 
  agreement 
  with 
  the 
  

   general 
  statement 
  that 
  a 
  surface 
  of 
  H 
  2 
  2 
  exposed 
  to 
  sunshine 
  

   discharges 
  negative 
  electrification 
  more 
  rapidly 
  than 
  a 
  water 
  

   surface. 
  

  

  