﻿42 
  Mr. 
  R. 
  F. 
  D'Arcy 
  on 
  the 
  

  

  two 
  known 
  planes. 
  These 
  planes 
  are 
  the 
  position 
  of 
  the 
  

   horizontal 
  at 
  noon 
  and 
  the 
  same 
  plane 
  turned 
  90° 
  round 
  the 
  

   axis 
  of 
  the 
  earth. 
  Consequently 
  the 
  absolute 
  direction 
  of 
  

   drift 
  is 
  determined, 
  and 
  the 
  values 
  of 
  I 
  for 
  noon 
  and 
  6 
  p.m. 
  

   can 
  be 
  calculated— 
  say 
  1^ 
  I 
  2 
  . 
  

  

  The 
  magnitudes 
  of 
  the 
  shift 
  of 
  the 
  fringes 
  then 
  give 
  

  

  (X/cos 
  h 
  + 
  |)E 
  2 
  cos 
  2 
  Ij 
  and 
  (X/cos 
  I 
  2 
  + 
  J)E 
  2 
  cos 
  2 
  1 
  2 
  , 
  

  

  where 
  H 
  is 
  the 
  ratio 
  of 
  total 
  drift 
  to 
  velocity 
  of 
  light. 
  Hence 
  

   X 
  and 
  H 
  can 
  be 
  separately 
  determined. 
  

  

  III. 
  The 
  Decomposition 
  of 
  Hydrogen 
  Peroxide 
  by 
  Light, 
  and 
  

   the 
  Electrical 
  Discharging 
  Action 
  of 
  this 
  Decomposition. 
  By 
  

   R. 
  F. 
  D'Akcy, 
  M.A* 
  

  

  THE 
  progress 
  of 
  knowledge 
  o%the 
  subject 
  of 
  the 
  probable 
  

   modes 
  of 
  development 
  of 
  electrical 
  phenomena 
  in 
  the 
  

   atmosphere 
  during 
  the 
  last 
  few 
  years 
  has 
  been 
  rapid. 
  The 
  

   difference 
  in 
  behaviour 
  of 
  positive 
  and 
  negative 
  ions 
  as 
  

   nuclei 
  of 
  condensation, 
  combined 
  with 
  the 
  proved 
  existence 
  

   of 
  ions 
  as 
  being 
  normally 
  present 
  in 
  the 
  air, 
  may 
  be 
  considered 
  

   as 
  establishing 
  the 
  precipitation 
  theory 
  of 
  atmospheric 
  

   electricity. 
  

  

  The 
  object 
  of 
  the 
  present 
  paper 
  is 
  to 
  give 
  an 
  account 
  of 
  

   experiments 
  which 
  were 
  undertaken 
  with 
  the 
  view 
  of 
  investi- 
  

   gating 
  a 
  chemical 
  action 
  to 
  account 
  for 
  a 
  possible 
  origin 
  of 
  

   these 
  charged 
  particles. 
  It 
  may 
  be 
  stated 
  that 
  the 
  view 
  

   adopted 
  is 
  that 
  such 
  a 
  possible 
  action 
  is 
  the 
  decomposition 
  of 
  

   hydrogen 
  peroxide 
  by 
  light\. 
  The 
  water 
  formed 
  by 
  the 
  

   decomposition 
  being 
  positively 
  charged, 
  and 
  the 
  oxygen 
  

   (whatever 
  its 
  atomicity 
  may 
  be) 
  being 
  negatively 
  charged. 
  

  

  The 
  formation 
  of 
  hydrogen 
  peroxide 
  in 
  nature 
  is 
  a 
  well 
  

   recognized 
  fact. 
  The 
  probable 
  formation 
  of 
  hydrogen 
  per- 
  

   oxide 
  by 
  ultra-violet 
  light 
  in 
  moist 
  oxygen 
  has 
  been 
  indicated 
  

   by 
  C. 
  T. 
  R. 
  Wilson 
  (Phil. 
  Trans. 
  1899); 
  the 
  minute 
  drops 
  of 
  

   hydrogen-peroxide 
  solution 
  being 
  uncharged. 
  The 
  main 
  

   ideas 
  of 
  the 
  present 
  paper 
  are 
  to 
  suggest 
  that 
  hydrogen 
  peroxide 
  

   when 
  split 
  up 
  yields 
  two 
  parts 
  which 
  are 
  oppositely 
  charged, 
  

   and 
  that 
  in 
  nature 
  this 
  splitting 
  up 
  may 
  be 
  brought 
  about 
  

   by 
  the 
  action 
  of 
  light. 
  

  

  The 
  experiments 
  made 
  were 
  of 
  two 
  kinds. 
  Some 
  were 
  

   made 
  to 
  investigate 
  the 
  conditions 
  under 
  which 
  hydrogen 
  

   peroxide 
  is 
  decomposed 
  by 
  light, 
  as, 
  although 
  this 
  effect 
  has 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

  

  t 
  The 
  possible 
  formation 
  of 
  ions 
  by 
  supersaturation 
  has 
  been 
  con- 
  

   sidered 
  by 
  C. 
  T. 
  R. 
  Wilson, 
  Phil. 
  Trans, 
  vol. 
  exciii. 
  A. 
  1900. 
  

  

  