﻿THE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  [SIXTH 
  SERIES.] 
  

  

  DEC 
  EMBER 
  1909, 
  

  

  LXXXIX. 
  Positive 
  Electricity, 
  By 
  Sir 
  J. 
  J. 
  Thomson, 
  

   Professor 
  of 
  Ed'peiimental 
  Physics, 
  Camhridge 
  *. 
  

  

  THE 
  most 
  important 
  questions 
  to 
  be 
  settled 
  as 
  to 
  the 
  

   nature 
  o£ 
  positive 
  electricity 
  are 
  : 
  — 
  (1) 
  Does 
  a 
  definite 
  

   unit 
  of 
  positive 
  electricity 
  exist 
  ? 
  (2) 
  If 
  so, 
  what 
  is 
  the 
  size 
  

   of 
  ihe 
  unit 
  ? 
  

  

  Question 
  (1) 
  may 
  perhaps 
  be 
  made 
  clearer 
  by 
  considering 
  

   a 
  definite 
  case. 
  Suppose 
  we 
  could 
  get 
  a 
  pure 
  gas, 
  say 
  oxygen 
  

   or 
  nitrogen, 
  would 
  it 
  be 
  possible 
  to 
  get 
  in 
  such 
  a 
  gas, 
  positively 
  

   charged 
  particles 
  smaller 
  than 
  the 
  residue 
  left, 
  when 
  a 
  cor- 
  

   puscle 
  is 
  removed 
  from 
  an 
  atom 
  of 
  oxygen 
  or 
  nitrogen 
  ? 
  

  

  Again, 
  we 
  know 
  that 
  we 
  can 
  get 
  negative 
  particles 
  of 
  the 
  

   same 
  kind 
  whether 
  we 
  extract 
  them 
  from 
  oxygen, 
  hydrogen, 
  

   or 
  nitrogen. 
  Is 
  there 
  anything 
  analogous 
  to 
  this 
  in 
  the 
  

   case 
  of 
  positive 
  electricity 
  ? 
  Can 
  we 
  in 
  short 
  get 
  positively 
  

   •electrified 
  particles 
  of 
  the 
  same 
  kind 
  from 
  different 
  gases 
  ? 
  

  

  Our 
  knowledge 
  of 
  charged 
  j)Ositive 
  particles 
  (other 
  than 
  

   a 
  particles) 
  has 
  been 
  derived 
  from 
  two 
  sources 
  : 
  (1) 
  the 
  study 
  

   of 
  positive 
  particles 
  in 
  systems 
  of 
  positive 
  rays 
  found 
  ia 
  

   vacuum-tubes 
  ; 
  (2) 
  the 
  study 
  of 
  the 
  velocity 
  of 
  the 
  positive 
  

   ions 
  in 
  ionized 
  gas. 
  

  

  To 
  begin 
  with 
  the 
  first 
  method. 
  The 
  two 
  sets 
  of 
  positive 
  

   rays 
  which 
  have 
  been 
  most 
  closely 
  studied 
  are, 
  firstly, 
  the 
  

   Canalstrahlen 
  which 
  are 
  found 
  passing 
  through 
  a 
  perforated 
  

  

  * 
  A 
  paper 
  introducing 
  a 
  discussion 
  on 
  this 
  subject 
  read 
  on 
  August 
  30, 
  

   1909, 
  at 
  tbe 
  Winnipeg 
  meeting 
  of 
  the 
  British 
  Association. 
  Communicated 
  

   bv 
  the 
  Author. 
  

  

  ' 
  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  18. 
  No. 
  108. 
  Dec. 
  1909. 
  3 
  K 
  

  

  