﻿Constituent 
  of 
  the 
  Atmosphere. 
  283 
  

  

  Although 
  it 
  seemed 
  almost 
  impossible 
  that 
  these 
  residues 
  

   could 
  be 
  either 
  nitrogen 
  or 
  hydrogen, 
  some 
  anxiety 
  was 
  not 
  

   unnatural, 
  seeing 
  that 
  the 
  final 
  sparking 
  took 
  place 
  under 
  some- 
  

   what 
  abnormal 
  conditions. 
  The 
  space 
  was 
  very 
  restricted, 
  and 
  

   the 
  temperature 
  (and 
  with 
  it 
  the 
  proportion 
  of 
  aqueous 
  vapor) 
  

   was 
  unduly 
  high. 
  But 
  any 
  doubts 
  that 
  were 
  felt 
  upon 
  this 
  

   score 
  were 
  removed 
  by 
  comparison 
  experiments 
  in 
  which 
  the 
  

   whole 
  quantity 
  of 
  air 
  operated 
  on 
  was 
  very 
  small. 
  Thus, 
  when 
  

   a 
  mixture 
  of 
  5 
  CC 
  of 
  air 
  with 
  T 
  cc 
  of 
  oxygen 
  was 
  sparked 
  for 
  1J 
  

   hours, 
  the 
  residue 
  was 
  0*47 
  cc 
  , 
  and 
  after 
  removal 
  of 
  oxygen 
  

   0*06 
  cc 
  . 
  Several 
  repetitions 
  having 
  given 
  similar 
  results, 
  it 
  

   became 
  clear 
  that 
  the 
  final 
  residue 
  did 
  not 
  depend 
  upon 
  any- 
  

   thing 
  that 
  might 
  happen 
  when 
  sparks 
  passed 
  through 
  a 
  greatly 
  

   reduced 
  volume, 
  but 
  ivas 
  in 
  proportion 
  to 
  the 
  amount 
  of 
  air 
  

   operated 
  upon. 
  

  

  No 
  satisfactory 
  examination 
  of 
  the 
  residue 
  which 
  refused 
  to 
  

   be 
  oxidized 
  could 
  be 
  made 
  without 
  the 
  accumulation 
  of 
  a 
  

   larger 
  quantity. 
  This, 
  however, 
  was 
  difficult 
  of 
  attainment 
  at 
  

   the 
  time 
  in 
  question. 
  It 
  was 
  thought 
  that 
  the 
  cause 
  probably 
  

   lay 
  in 
  the 
  solubility 
  of 
  the 
  gas 
  in 
  water, 
  a 
  suspicion 
  since 
  con- 
  

   firmed. 
  At 
  length, 
  however, 
  a 
  sufficiency 
  was 
  collected 
  to 
  

   allow 
  of 
  sparking 
  in 
  a 
  specially 
  constructed 
  tube, 
  when 
  a 
  com- 
  

   parison 
  with 
  the 
  air 
  spectrum, 
  taken 
  under 
  similar 
  conditions, 
  

   proved 
  that, 
  at 
  any 
  rate, 
  the 
  gas 
  was 
  not 
  nitrogen. 
  At 
  first 
  

   scarcely 
  a 
  trace 
  of 
  the 
  principal 
  nitrogen 
  lines 
  could 
  be 
  seen, 
  

   but 
  after 
  standing 
  over 
  water 
  for 
  an 
  hour 
  or 
  two 
  these 
  lines 
  

   became 
  apparent. 
  

  

  V. 
  Early 
  experiments 
  on 
  withdrawal 
  of 
  Nitrogen 
  from 
  Air 
  

   by 
  means 
  of 
  red-hot 
  Magnesium. 
  

  

  A 
  preliminary 
  experiment 
  carried 
  out 
  by 
  Mr. 
  Percy 
  Williams 
  

   on 
  the 
  absorption 
  of 
  atmospheric 
  nitrogen, 
  freed 
  from 
  oxygen 
  

   by 
  means 
  of 
  red-hot 
  copper, 
  in 
  which 
  the 
  gas 
  was 
  not 
  passed 
  

   over, 
  but 
  simply 
  allowed 
  to 
  remain 
  in 
  contact 
  with 
  the 
  metal, 
  

   gave 
  a 
  residue 
  of 
  density 
  14*88. 
  This 
  result, 
  although 
  not 
  

   conclusive, 
  was 
  encouraging 
  ; 
  and 
  an 
  attempt 
  was 
  made, 
  on 
  a 
  

   larger 
  scale, 
  by 
  passing 
  atmospheric 
  nitrogen 
  backwards 
  and 
  

   forwards 
  over 
  red-hot 
  magnesium 
  from 
  one 
  large 
  gas-holder 
  to 
  

   another 
  to 
  obtain 
  a 
  considerable 
  quantity 
  of 
  the 
  heavier 
  gas. 
  

   In 
  the 
  course 
  of 
  ten 
  days, 
  about 
  1500 
  cc 
  were 
  collected 
  and 
  

   transferred 
  gradually 
  to 
  a 
  mercury 
  gas-holder, 
  from 
  which 
  the 
  

   gas 
  was 
  passed 
  over 
  soda-lime, 
  phosphoric 
  anhydride, 
  magne- 
  

   sium 
  at 
  a 
  red 
  heat, 
  copper 
  oxide, 
  soda-lime, 
  and 
  phosphoric 
  

   anhydride 
  into 
  a 
  second 
  mercury 
  gas-holder. 
  After 
  some 
  days 
  

   the 
  gas 
  was 
  reduced 
  in 
  volume 
  to 
  about 
  200 
  cc 
  , 
  and 
  its 
  density 
  

   was 
  found 
  to 
  be 
  16'1. 
  After 
  further 
  absorption, 
  in 
  which 
  the 
  

  

  