﻿1875.] 
  

  

  Matter 
  in 
  the 
  Liquid 
  and 
  Gaseous 
  States. 
  

  

  521 
  

  

  How 
  far 
  this 
  relation 
  will 
  be 
  found 
  to 
  exist 
  under 
  other 
  conditions 
  of 
  

   temperature 
  and 
  pressure 
  will 
  appear 
  when 
  experiments 
  now 
  in 
  progress 
  

   are 
  brought 
  to 
  a 
  conclusion. 
  

  

  Law 
  of 
  Dalton. 
  — 
  This 
  law, 
  as 
  originally 
  enunciated 
  by 
  its 
  author, 
  is, 
  

   that 
  the 
  particles 
  of 
  one 
  gas 
  possess 
  no 
  repulsive 
  or 
  attractive 
  power 
  with 
  

   regard 
  to 
  the 
  particles 
  of 
  another. 
  " 
  Oxygen 
  gas," 
  he 
  states, 
  " 
  azotic 
  

   gas, 
  hydrogenous 
  gas, 
  carbonic 
  acid 
  gas, 
  aqueous 
  vapour, 
  and 
  probably 
  

   several 
  other 
  elastic 
  fluids 
  may 
  exist 
  in 
  company 
  under 
  any 
  pressure 
  and 
  

   at 
  any 
  temperature 
  without 
  any 
  regard 
  to 
  their 
  specific 
  gravities, 
  and 
  

   without 
  any 
  pressure 
  upon 
  one 
  another." 
  The 
  experiments 
  which 
  I 
  have 
  

   made 
  on 
  mixtures 
  of 
  carbonic 
  acid 
  and 
  nitrogen 
  have 
  occupied 
  a 
  larger 
  

   portion 
  of 
  time 
  than 
  all 
  I 
  have 
  yet 
  referred 
  to. 
  They 
  have 
  been 
  carried 
  

   to 
  the 
  great 
  pressure 
  of 
  283*9 
  atmospheres, 
  as 
  measured 
  in 
  glass 
  tubes 
  

   by 
  a 
  hydrogen 
  manometer, 
  at 
  which 
  pressure 
  a 
  mixture 
  of 
  3 
  volumes 
  

   carbonic 
  acid 
  and 
  4 
  volumes 
  nitrogen 
  was 
  reduced 
  at 
  7 
  0, 
  6 
  to 
  -g-i-g- 
  of 
  its 
  

   volume 
  without 
  liquefaction 
  of 
  the 
  carbonic 
  acid. 
  As 
  this 
  note 
  has 
  

   already 
  extended 
  to 
  an 
  unusual 
  length, 
  I 
  will 
  not 
  now 
  attempt 
  to 
  give 
  

   an 
  analysis 
  of 
  these 
  experiments, 
  but 
  shall 
  briefly 
  state 
  their 
  general 
  

   results. 
  The 
  most 
  important 
  of 
  these 
  results 
  is 
  the 
  lowering 
  of 
  the 
  

   critical 
  point 
  by 
  admixture 
  with 
  a 
  non-condensable 
  gas. 
  Thus 
  in 
  the 
  

   mixture 
  mentioned 
  above 
  of 
  carbonic 
  acid 
  and 
  nitrogen, 
  no 
  liquid 
  was 
  

   formed 
  at 
  any 
  pressure 
  till 
  the 
  temperature 
  was 
  reduced 
  below 
  —20° 
  0. 
  

   Even 
  the 
  addition 
  of 
  only 
  T 
  l 
  - 
  of 
  its 
  volume 
  of 
  air 
  or 
  nitrogen 
  to 
  car- 
  

   bonic 
  acid 
  gas 
  will 
  lower 
  the 
  critical 
  point 
  several 
  degrees. 
  Finally, 
  

   these 
  experiments 
  leave 
  no 
  doubt 
  that 
  the 
  law 
  of 
  Dalton 
  entirely 
  fails 
  

   under 
  high 
  pressures, 
  where 
  one 
  of 
  the 
  gases 
  is 
  at 
  a 
  temperature 
  not 
  

   greatly 
  above 
  its 
  critical 
  point. 
  The 
  anomalies 
  observed 
  in 
  the 
  tension 
  

   of 
  the 
  vapour 
  of 
  water 
  when 
  alone 
  and 
  when 
  mixed 
  with 
  air 
  find 
  their 
  

   real 
  explanation 
  in 
  the 
  fact 
  that 
  the 
  law 
  of 
  Dalton 
  is 
  only 
  approximately 
  

   true 
  in 
  the 
  case 
  of 
  mixtures 
  of 
  air 
  and 
  aqueous 
  vapour 
  at 
  the 
  ordinary 
  

   pressure 
  and 
  temperature 
  of 
  the 
  atmosphere, 
  and 
  do 
  not 
  depend, 
  as 
  has 
  

   been 
  alleged, 
  on 
  any 
  disturbing 
  influence 
  produced 
  by 
  a 
  hygroscopic 
  

   action 
  of 
  the 
  sides 
  of 
  the 
  containing 
  vessel. 
  The 
  law 
  of 
  Dalton, 
  in 
  

   short, 
  like 
  the 
  laws 
  of 
  Boyle 
  and 
  Gray-Lussac, 
  only 
  holds 
  good 
  in 
  the 
  

   case 
  of 
  gaseous 
  bodies 
  which 
  are 
  at 
  feeble 
  pressures 
  and 
  at 
  temperatures 
  

   greatly 
  above 
  their 
  critical 
  points. 
  Under 
  other 
  conditions 
  these 
  laws 
  

   are 
  interfered 
  with 
  ; 
  and 
  in 
  certain 
  conditions 
  (such 
  as 
  some 
  of 
  those 
  

   described 
  in 
  this 
  note) 
  the 
  interfering 
  causes 
  become 
  so 
  powerful 
  as 
  

   practically 
  to 
  efface 
  them. 
  

  

  