﻿[ 
  121 
  ] 
  

  

  VII. 
  Condensation 
  of 
  the 
  Actinium 
  and 
  Thorium 
  Emanations. 
  

   By 
  S. 
  Kinoshita*. 
  

  

  IN 
  their 
  well-known 
  experiment, 
  Rutherford 
  and 
  Soddy 
  f 
  

   have 
  shown 
  that 
  the 
  radium 
  emanation 
  begins 
  to 
  con- 
  

   dense 
  at 
  —150° 
  C, 
  and 
  that 
  there 
  is 
  only 
  a 
  slight 
  difference 
  

   between 
  the 
  temperatures 
  of 
  complete 
  volatilization 
  and 
  o£ 
  

   complete 
  condensation. 
  They 
  also 
  showed 
  that 
  the 
  ema- 
  

   nation 
  of: 
  thorium 
  behaved 
  in 
  a 
  very 
  different 
  manner. 
  

   The 
  emanation 
  began 
  to 
  condense 
  at 
  —120° 
  C, 
  but 
  a 
  

   much 
  lower 
  temperature, 
  viz. 
  about 
  — 
  150° 
  C, 
  was 
  required 
  

   in 
  order 
  to 
  completely 
  condense 
  it. 
  The 
  temperature, 
  at 
  

   which 
  the 
  same 
  number 
  of 
  particles 
  o£ 
  the 
  emanation 
  

   remained 
  uncondensed, 
  was 
  different 
  when 
  different 
  gases 
  

   were 
  employed 
  to 
  convey 
  the 
  emanation. 
  Thus 
  the 
  tem- 
  

   perature 
  was 
  higher 
  for 
  hydrogen 
  than 
  for 
  oxygen, 
  but 
  

   the 
  difference 
  was 
  not 
  more 
  than 
  3 
  degrees 
  for 
  the 
  half 
  

   value. 
  A 
  greater 
  proportion 
  was 
  found 
  to 
  condense 
  when 
  

   the 
  emanation 
  was 
  left 
  for 
  90 
  seconds 
  in 
  the 
  spiral 
  than 
  for 
  

   30 
  seconds. 
  The 
  different 
  behaviour 
  of 
  the 
  two 
  emanations 
  

   was 
  ascribed 
  by 
  them 
  to 
  the 
  great 
  difference 
  in 
  the 
  number 
  

   of 
  particles 
  of 
  emanation 
  present. 
  

  

  Goldstein 
  % 
  made 
  some 
  experiments 
  on 
  the 
  condensation 
  of 
  

   the 
  actinium 
  emanation 
  by 
  a 
  different 
  method, 
  using 
  a 
  pre- 
  

   paration 
  of 
  the 
  " 
  Emanationskorper 
  " 
  of 
  Giesel, 
  now 
  known 
  

   as 
  actinium. 
  An 
  exhausted 
  glass 
  tube 
  was 
  taken, 
  at 
  one 
  end 
  

   of 
  which 
  was 
  placed 
  the 
  actinium 
  preparation, 
  and 
  at 
  the 
  

   other 
  a 
  zinc-sulphide 
  screen. 
  The 
  emanation 
  diffused 
  along 
  

   the 
  tube 
  and 
  produced 
  phosphorescence 
  on 
  the 
  screen. 
  The 
  

   luminosity 
  was 
  found 
  to 
  decrease 
  when 
  a 
  glass 
  tube, 
  

   cooled 
  by 
  liquid 
  air, 
  was 
  placed 
  between 
  the 
  actinium 
  and 
  

   the 
  screen, 
  showing 
  that 
  some 
  of 
  the 
  emanation 
  was 
  con- 
  

   densed 
  on 
  the 
  walls 
  of 
  the 
  tube. 
  This 
  experiment, 
  which 
  

   was 
  made 
  in 
  the 
  early 
  stage 
  of 
  the 
  enquiry, 
  lacks 
  quantitative 
  

   precision. 
  

  

  The 
  determination 
  of 
  the 
  temperatures 
  of 
  condensation 
  

   and 
  volatilization 
  of 
  actinium 
  emanation 
  has 
  been 
  carried 
  out 
  

   by 
  the 
  writer, 
  using 
  the 
  electrical 
  method 
  which 
  has 
  been 
  

   adopted 
  by 
  Rutherford 
  and 
  Soddy 
  for 
  thorium 
  and 
  radium 
  

   emanations. 
  

  

  A 
  gas 
  conveying 
  a 
  definite 
  amount 
  of 
  the 
  emanation 
  is 
  led 
  

   directly 
  into 
  a 
  partially 
  exhausted 
  copper 
  spiral, 
  the 
  tempe- 
  

   rature 
  of 
  which, 
  while 
  rising 
  slowly 
  from 
  that 
  of 
  liquid 
  air, 
  

  

  * 
  Communicated 
  by 
  Prof. 
  E. 
  Kutherford, 
  F.K.S. 
  

  

  f 
  Phil. 
  Mag. 
  vol. 
  v. 
  p. 
  361 
  (1903). 
  

  

  % 
  Berichte 
  d. 
  deutsch. 
  phys. 
  GesellschafU 
  p. 
  393 
  (1903). 
  

  

  