﻿632 
  Mr. 
  F. 
  Soddy 
  on 
  the 
  Relation 
  

  

  extent, 
  so 
  that 
  a 
  thorough 
  radioactive 
  survey 
  cannot 
  fail 
  to 
  

   be 
  of 
  interest 
  and 
  advantage. 
  

  

  Summary. 
  

  

  (1) 
  The 
  amount 
  of 
  radium 
  which 
  would 
  be 
  in 
  equilibrium 
  

  

  with 
  the 
  average 
  amount 
  of 
  radium 
  emanation 
  

   present 
  in 
  a 
  cubic 
  metre 
  of 
  air, 
  as 
  measured 
  at 
  

   Montreal 
  at 
  intervals 
  extending 
  over 
  a 
  year, 
  1907-8, 
  

   is 
  60 
  xlO- 
  12 
  grain. 
  

  

  (2) 
  The 
  amount 
  of 
  radium 
  emanation 
  in 
  the 
  atmosphere 
  

  

  varied 
  so 
  that 
  the 
  maximum 
  is 
  to 
  the 
  minimum 
  as 
  

   about 
  7 
  is 
  to 
  1. 
  

  

  (3) 
  The 
  amounts 
  in 
  summer 
  and 
  in 
  winter 
  are 
  not 
  widely 
  

  

  different, 
  and 
  large 
  changes 
  of 
  temperature 
  appear 
  

   to 
  have 
  little 
  or 
  no 
  direct 
  influence 
  on 
  the 
  quantity. 
  

   (I) 
  The 
  approach 
  of 
  a 
  deep 
  cyclone, 
  accompanied 
  by 
  heavy 
  

   rain 
  or 
  a 
  quick 
  thaw 
  of 
  snow, 
  cause 
  an 
  increase, 
  

   whilst 
  anticyclonic 
  conditions, 
  with 
  dry 
  or 
  very 
  cold 
  

   weather, 
  give 
  a 
  decrease 
  of 
  the 
  radium 
  emanation 
  in 
  

   the 
  air. 
  

  

  I 
  am 
  grateful 
  to 
  Professor 
  Rutherford 
  for 
  proposing 
  to 
  

   me 
  this 
  experimental 
  work 
  and 
  for 
  suggesting 
  the 
  general 
  

   methods 
  adopted. 
  

  

  Hornsea, 
  27th 
  June, 
  ]908. 
  

  

  LII. 
  The 
  Relation 
  between 
  Uranium 
  and 
  Radium. 
  III.* 
  

   By 
  Frederick 
  Soddy, 
  M.A.\ 
  

  

  MORE 
  than 
  a 
  year 
  has 
  elapsed 
  since 
  the 
  last 
  published 
  

   tests 
  in 
  the 
  second 
  series 
  of 
  experiments 
  with 
  large 
  

   quantities 
  of 
  uranium, 
  purified 
  with 
  great 
  care 
  by 
  Mr. 
  T. 
  D. 
  

   Mackenzie. 
  The 
  subsequent 
  tests 
  on 
  these 
  preparations 
  and 
  

   some 
  new 
  experiments 
  are 
  given 
  in 
  the 
  present 
  paper. 
  The 
  

   only 
  change 
  of 
  method 
  to 
  be 
  recorded 
  is 
  the 
  use 
  of 
  a 
  glass 
  

   electroscope 
  of 
  globular 
  form, 
  silvered 
  internally, 
  which 
  

   being 
  air-tight 
  and 
  capable 
  of 
  standing 
  a 
  vacuum, 
  is 
  more 
  

   suited 
  for 
  the 
  measurement 
  of 
  minute 
  quantities 
  of 
  radium 
  

   emanation, 
  as 
  the 
  observations 
  can 
  be 
  extended 
  over 
  longer 
  

   intervals 
  without 
  fear 
  of 
  loss. 
  In 
  Experiments 
  I. 
  and 
  II. 
  the 
  

   emanation 
  has 
  been 
  extracted 
  by 
  the 
  mercury 
  pump 
  exactly 
  

   as 
  before 
  ; 
  but 
  this 
  arrangement 
  has 
  now 
  been 
  dispensed 
  

   with 
  and 
  the 
  solutions 
  sealed 
  up 
  in 
  large 
  flasks. 
  Subsequent 
  

  

  * 
  I. 
  Soddy, 
  Phil. 
  Mag. 
  June 
  190-5, 
  p. 
  7(38. 
  II. 
  Soddy 
  and 
  Mackenzie, 
  

   Phil. 
  Mag-. 
  Aug. 
  1907, 
  p. 
  272. 
  

   t 
  Communicated 
  by 
  the 
  Author. 
  

  

  