﻿458 
  The 
  Influence 
  of 
  Dissolved 
  Substances 
  on 
  Clouds. 
  

  

  forming 
  a 
  nucleus 
  on 
  which 
  the 
  drop 
  can 
  be 
  re-formed 
  after 
  it 
  

   has 
  been 
  evaporated 
  by 
  the 
  acid. 
  

  

  The 
  behaviour 
  of 
  the 
  electrification 
  with 
  a 
  glass-wool 
  plug 
  

   is 
  interesting. 
  With 
  a 
  solution 
  the 
  particles 
  left 
  after 
  passing 
  

   through 
  the 
  acid 
  must 
  be 
  larger 
  than 
  those 
  left 
  when 
  water 
  

   is 
  sprayed. 
  Yet 
  the 
  electrification 
  gets 
  through 
  the 
  plug- 
  

   only 
  in 
  the 
  former 
  case. 
  The 
  fact 
  that 
  the 
  electrification 
  

   which 
  cannot 
  get 
  through 
  the 
  plug 
  is 
  also 
  not 
  easily 
  blown 
  

   out, 
  whilst 
  that 
  which 
  goes 
  through 
  the 
  plug 
  is 
  readily 
  almost 
  

   entirely 
  blown 
  out, 
  shows 
  that 
  the 
  smaller 
  electrified 
  particles, 
  

   as 
  we 
  should 
  expect, 
  are 
  much 
  more 
  rapidly 
  driven 
  to 
  the 
  

   sides 
  of 
  the 
  flask 
  and 
  discharged 
  than 
  the 
  larger 
  particles. 
  

   In 
  the 
  case 
  of 
  the 
  plug, 
  also, 
  the 
  smaller 
  particles, 
  owing 
  to 
  

   their 
  more 
  rapid 
  motion 
  and 
  greater 
  velocity 
  under 
  electric 
  

   forces, 
  are 
  much 
  more 
  readily 
  caught 
  by 
  the 
  fibres. 
  

  

  The 
  charged 
  gases 
  obtained 
  by 
  the 
  action 
  of 
  Rontgen 
  rays 
  

   are 
  unable 
  to 
  carry 
  their 
  charge 
  through 
  a 
  glass-wool 
  plug, 
  

   whilst 
  the 
  far 
  larger 
  particles 
  which 
  form 
  the 
  nuclei 
  in 
  the 
  

   above 
  experiments 
  are 
  able 
  to 
  do 
  this. 
  It 
  has 
  been 
  supposed 
  

   that 
  the 
  fact 
  that 
  the 
  charge 
  of 
  Rontgenized 
  gases 
  is 
  stopped 
  

   by 
  glass 
  wool 
  shows 
  that 
  the 
  charge 
  is 
  upon 
  large 
  particles, 
  

   but 
  the 
  above 
  observations 
  lend 
  additional 
  support, 
  if 
  any 
  is 
  

   needed, 
  to 
  the 
  view 
  that 
  the 
  stoppage 
  of 
  the 
  charge 
  is 
  due 
  to 
  

   the 
  rapid 
  velocity 
  with 
  which 
  such 
  very 
  small 
  particles 
  move 
  

   causing 
  them 
  to 
  strike 
  the 
  fibres 
  of 
  the 
  wool 
  plug. 
  

  

  The 
  fact 
  which 
  I 
  have 
  observed, 
  that 
  a 
  charged 
  cloud 
  of 
  

   water 
  after 
  evaporation 
  over 
  sulphuric 
  acid 
  does 
  not 
  reappear 
  

   over 
  water 
  although 
  the 
  charge 
  is 
  not 
  stopped, 
  does 
  not 
  seem 
  

   to 
  favour 
  the 
  view 
  that 
  the 
  formation 
  of 
  clouds 
  in 
  newly 
  

   prepared 
  gases 
  is 
  an 
  electrical 
  phenomenon. 
  It 
  is, 
  however, 
  

   possible 
  that 
  in 
  my 
  experiments 
  the 
  number 
  of 
  particles 
  on 
  

   which 
  the 
  charge 
  was 
  distributed 
  was 
  small 
  compared 
  with 
  the 
  

   number 
  present 
  in 
  newly 
  prepared 
  gases. 
  Against 
  this 
  we 
  

   have 
  the 
  fact 
  that 
  nearly 
  all 
  the 
  charge 
  which 
  passed 
  through 
  

   glass 
  wool 
  could 
  be 
  readily 
  blown 
  out, 
  which 
  seems 
  to 
  show 
  

   that 
  it 
  was 
  distributed 
  over 
  a 
  large 
  number 
  of 
  particles. 
  

  

  The 
  electrification 
  of 
  hydrogen 
  prepared 
  by 
  the 
  action 
  of 
  

   50 
  per 
  cent, 
  sulphuric 
  acid 
  on 
  iron 
  wire 
  at 
  80° 
  C, 
  after 
  pass- 
  

   ing 
  through 
  sulphuric 
  acid 
  and 
  a 
  glass-wool 
  plug, 
  could 
  be 
  

   almost 
  entirely 
  blown 
  out 
  (Townsend, 
  loc. 
  cit. 
  p. 
  246). 
  In 
  

   this 
  it 
  exactly 
  resembles 
  the 
  electrification 
  on 
  a 
  cloud 
  of 
  

   dilute 
  sulphuric 
  acid 
  as 
  I 
  have 
  shown. 
  This 
  similarity 
  be- 
  

   tween 
  the 
  behaviour 
  of 
  the 
  newly 
  prepared 
  gases 
  and 
  the 
  air 
  

   containing 
  a 
  cloud 
  consisting 
  of 
  a 
  dilute 
  solution 
  suggests 
  the 
  

   conclusion 
  that 
  the 
  clouds 
  formed 
  in 
  the 
  newly 
  prepared 
  

   gases 
  also 
  consist 
  of 
  a 
  dilute 
  solution 
  of 
  some 
  substance, 
  and 
  

   that 
  their 
  reappearance 
  over 
  water 
  after 
  being 
  bubbled 
  through 
  

  

  