﻿144 
  Mr. 
  John 
  S. 
  Townsend 
  on 
  Electrical 
  

  

  21. 
  The 
  discharging-power 
  of 
  a 
  tube 
  in 
  a 
  vertical 
  position 
  

   is, 
  as 
  we 
  should 
  expect, 
  greatly 
  diminished 
  by 
  having 
  the 
  gas 
  

   moist, 
  as 
  the 
  electric 
  force 
  is 
  then 
  too 
  small 
  to 
  have 
  any 
  

   appreciable 
  effect 
  in 
  causing 
  the 
  drops 
  to 
  move 
  towards 
  the 
  

   sides. 
  Thus, 
  in 
  an 
  experiment 
  similar 
  to 
  that 
  explained 
  in 
  

   Section 
  15, 
  the 
  hydrogen, 
  instead 
  of 
  being 
  bubbled 
  through 
  

   sulphuric 
  acid 
  before 
  entering 
  C, 
  was 
  bubbled 
  through 
  water, 
  

   and 
  it 
  was 
  found 
  that 
  when 
  acquired 
  a 
  charge 
  of 
  fourteen 
  

   per 
  minute, 
  the 
  inductor 
  acquired 
  seventy-five 
  per 
  minute 
  ; 
  

   whereas 
  if 
  a 
  similarly 
  charged 
  dry 
  gas 
  had 
  been 
  used, 
  C 
  would 
  

   have 
  acquired 
  a 
  charge 
  at 
  the 
  rate 
  of 
  twenty-eight 
  per 
  

   minute, 
  and 
  the 
  inductor 
  at 
  the 
  rate 
  of 
  sixty-two. 
  

  

  The 
  same 
  property 
  holds 
  in 
  the 
  case 
  of 
  charged 
  oxygen. 
  

   Thus 
  when 
  the 
  gas 
  carries 
  a 
  cloud, 
  only 
  four 
  divisions 
  per 
  

   minute 
  were 
  acquired 
  by 
  C, 
  whereas 
  a 
  similarly 
  charged 
  dry 
  

   gas 
  would 
  have 
  given 
  seven 
  divisions 
  per 
  minute. 
  The 
  loss 
  

   of 
  charge 
  of 
  the 
  clouded 
  gas 
  in 
  passing 
  through 
  a 
  vertical 
  

   tube 
  is 
  due 
  to 
  the 
  unevenness 
  in 
  the 
  motion 
  and 
  the 
  accidental 
  

   contact 
  of 
  the 
  cloud 
  with 
  the 
  sides. 
  

  

  Diffusion, 
  

  

  22. 
  Experiments 
  were 
  performed 
  on 
  the 
  diffusion 
  of 
  charged 
  

   gases 
  in 
  order 
  to 
  find 
  out 
  whether 
  any 
  of 
  the 
  charge 
  can 
  pass 
  

   through 
  porous 
  earthenware. 
  The 
  apparatus 
  which 
  was 
  used 
  

   in 
  these 
  experiments 
  is 
  shown 
  in 
  fig. 
  5. 
  It 
  consists 
  of 
  

   two 
  cylinders, 
  the 
  outer 
  Q 
  was 
  of 
  tin, 
  and 
  the 
  inner 
  P 
  was 
  

   a 
  porous 
  porcelain 
  vessel 
  fixed 
  by 
  means 
  of 
  corks 
  (C) 
  to 
  the 
  

   tin 
  cylinder. 
  The 
  porous 
  vessel 
  had 
  one 
  aperture 
  which 
  was 
  

   fitted 
  with 
  an 
  indiarubber 
  stopper 
  carrying 
  two 
  tubes 
  pro- 
  

   jecting 
  through 
  the 
  sides 
  of 
  Q 
  at 
  D 
  1 
  and 
  D 
  2 
  . 
  The 
  tube 
  

   T 
  was 
  broken, 
  and 
  fitted 
  with 
  a 
  paraffin 
  tunnel 
  for 
  purposes 
  

   of 
  insulation, 
  and 
  the 
  tube 
  U 
  dipped 
  into 
  a 
  sulphuric-acid 
  

   bottle, 
  and 
  so 
  acted 
  as 
  a 
  manometer. 
  The 
  outer 
  cylinder 
  had 
  

   two 
  apertures 
  at 
  E 
  and 
  F; 
  the 
  tube 
  R 
  from 
  E 
  led 
  into 
  a 
  

   large 
  insulated 
  inductor; 
  and 
  the 
  tube 
  from 
  F 
  was 
  connected 
  

   through 
  a 
  paraffin 
  tunnel 
  to 
  the 
  delivery-tube 
  of 
  a 
  sulphuric- 
  

   acid 
  bottle. 
  

  

  Before 
  performing 
  an 
  experiment 
  it 
  is 
  necessary 
  to 
  

   thoroughly 
  dry 
  the 
  whole 
  apparatus 
  ; 
  this 
  was 
  done 
  by 
  blow- 
  

   ing 
  dry 
  air 
  through 
  T 
  and 
  F. 
  The 
  charged 
  hydrogen 
  from 
  

   a 
  sulphuric-acid 
  electrolyte 
  was 
  dried 
  and 
  allowed 
  to 
  enter 
  

   the 
  cylinder 
  P 
  through 
  T. 
  

  

  The 
  bellows 
  are 
  connected 
  to 
  the 
  tube 
  S, 
  and 
  a 
  gentle 
  

   current 
  of 
  air 
  is 
  blown 
  into 
  the 
  cylinder 
  through 
  F. 
  The 
  

   cylinder 
  Q 
  is 
  connected 
  to 
  earth, 
  and 
  the 
  inductor 
  into 
  which 
  

  

  