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  Scientific 
  Intelligence. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistky 
  and 
  Physics. 
  

  

  1. 
  On 
  the 
  Passage 
  of 
  Argon 
  through 
  thin 
  Films 
  of 
  India- 
  

   rubber 
  ; 
  by 
  Lord 
  Rayleigh. 
  — 
  Soon 
  after 
  the 
  discovery 
  of 
  argon 
  

   it 
  was 
  thought 
  desirable 
  to 
  compare 
  the 
  percolation 
  of 
  the 
  gas 
  

   through 
  india-rubber 
  with 
  that 
  of 
  nitrogen, 
  and 
  Sir 
  W. 
  Roberts- 
  

   Austen 
  kindly 
  gave 
  me 
  some 
  advice 
  upon 
  the 
  subject. 
  The 
  pro- 
  

   posal 
  was 
  simply 
  to 
  allow 
  atmospheric 
  air 
  to 
  percolate 
  through 
  

   the 
  rubber 
  film 
  into 
  a 
  vacuum, 
  after 
  the 
  manner 
  of 
  Graham, 
  and 
  

   then 
  to 
  determine 
  the 
  proportion 
  of 
  argon. 
  It 
  will 
  be 
  remem- 
  

   bered 
  that 
  Graham 
  found 
  that 
  the 
  percentage 
  of 
  oxygen 
  was 
  

   raised 
  in 
  this 
  manner 
  from 
  the 
  21 
  of 
  the 
  atmosphere 
  to 
  about 
  40. 
  

   At 
  the 
  time 
  the 
  experiment 
  fell 
  through, 
  but 
  during 
  the 
  last 
  year 
  

   I 
  have 
  carried 
  it 
  out 
  with 
  the 
  assistance 
  of 
  Mr. 
  Gordon. 
  

  

  The 
  rubber 
  balloon 
  was 
  first 
  charged 
  with 
  dry 
  boxwood 
  saw- 
  

   dust. 
  This 
  rather 
  troublesome 
  operation 
  was 
  facilitated 
  by 
  so 
  

   mounting 
  the 
  balloon 
  that 
  with 
  the 
  aid 
  of 
  an 
  air-pump 
  the 
  

   external 
  pressure 
  could 
  be 
  reduced. 
  When 
  sufficiently 
  distended 
  

   the 
  balloon 
  was 
  connected 
  with 
  a 
  large 
  Toepler 
  pump, 
  into 
  the 
  

   vacuous 
  head 
  of 
  which 
  the 
  diffused 
  gases 
  could 
  collect. 
  At 
  

   intervals 
  they 
  were 
  drawn 
  off 
  in 
  the 
  usual 
  way. 
  

  

  The 
  diffusion 
  was 
  not 
  conducted 
  under 
  ideal 
  conditions. 
  In 
  

   order 
  to 
  make 
  the 
  most 
  of 
  the 
  time, 
  the. 
  apparatus 
  was 
  left 
  at 
  

   work 
  during 
  the 
  night, 
  so 
  that 
  by 
  the 
  morning 
  the 
  internal 
  pres- 
  

   sure 
  had 
  risen 
  to 
  perhaps 
  three 
  inches 
  of 
  mercury. 
  The 
  propor- 
  

   tion 
  of 
  oxygen 
  in 
  the 
  gas 
  collected 
  was 
  determined 
  from 
  time 
  to 
  

   time. 
  It 
  varied 
  from 
  34 
  per 
  cent 
  when 
  the 
  vacuum 
  was 
  bad 
  to 
  

   about 
  39 
  per 
  cent 
  when 
  the 
  vacuum 
  was 
  good. 
  On 
  an 
  average 
  it 
  

   was 
  estimated 
  that 
  the 
  proportion 
  of 
  oxygen 
  would 
  be 
  about 
  37 
  

   per 
  cent 
  of 
  the 
  whole. 
  The 
  total 
  quantity 
  of 
  diffused 
  gas 
  reck- 
  

   oned 
  at 
  atmospheric 
  pressure 
  was 
  about 
  300 
  cc 
  per 
  twenty-four 
  

   hours. 
  

  

  On 
  removal 
  from 
  the 
  pump 
  the 
  gas 
  was 
  introduced 
  into 
  an 
  

   inverted 
  flask 
  standing 
  over 
  alkali, 
  and 
  with 
  addition 
  of 
  oxygen 
  

   as 
  required 
  was 
  treated 
  with 
  the 
  electrical 
  discharge 
  from 
  a 
  trans- 
  

   former 
  in 
  connection 
  with 
  the 
  public 
  supply 
  of 
  alternating 
  cur- 
  

   rent. 
  In 
  this 
  way 
  the 
  nitrogen 
  w 
  r 
  as 
  gradually 
  oxidized 
  and 
  

   absorbed. 
  Towards 
  the 
  close 
  of 
  operations 
  the 
  gas 
  was 
  trans- 
  

   ferred 
  to 
  a 
  smaller 
  vessel, 
  where 
  it 
  was 
  further 
  sparked 
  until 
  no 
  

   further 
  contraction 
  occurred, 
  and 
  the 
  Hues 
  of 
  nitrogen 
  had 
  disap- 
  

   peared 
  from 
  the 
  spectrum. 
  The 
  excess 
  of 
  oxygen 
  was 
  then 
  

   removed 
  by 
  phosphorus. 
  

  

  It 
  remains 
  only 
  to 
  record 
  the 
  final 
  figures. 
  The 
  residue, 
  free 
  of 
  

   oxygen 
  and 
  nitrogen, 
  from 
  3205 
  cc 
  of 
  diffused 
  gas 
  was 
  39 
  cc 
  . 
  The 
  

   most 
  instructive 
  way 
  of 
  stating 
  the 
  result 
  is 
  perhaps 
  to 
  reckon 
  

   the 
  argon 
  as 
  a 
  percentage, 
  not 
  of 
  the 
  whole, 
  but 
  of 
  the 
  nitrogen 
  

   and 
  argon 
  only. 
  Of 
  the 
  3205 
  cc 
  total, 
  2020 
  cc 
  would 
  be 
  nitrogen 
  

  

  