﻿514 
  Dr. 
  Andrews 
  on 
  the 
  Physical 
  Properties 
  of 
  [June 
  17, 
  

  

  lessens 
  it 
  ; 
  and 
  without 
  attempting 
  to 
  allow 
  for 
  elongation 
  from, 
  the 
  sun 
  

   or 
  declination, 
  I 
  merely 
  compared 
  the 
  Ws 
  at 
  the 
  lunar 
  hours 
  21 
  and 
  3, 
  

   9 
  and 
  15. 
  I 
  only 
  took 
  the 
  first 
  six 
  months, 
  which 
  seemed 
  sufficient. 
  

   The 
  result 
  rather 
  surprised 
  me 
  ; 
  2418 
  observations 
  give 
  for 
  the 
  current 
  

   0*0906, 
  which, 
  allowing 
  for 
  the 
  omissions 
  above 
  mentioned 
  and 
  for 
  

   friction 
  at 
  the 
  earth's 
  surface, 
  must 
  be 
  very 
  near 
  the 
  truth. 
  Among 
  the 
  

   observations 
  are 
  two 
  above 
  40 
  and 
  three 
  above 
  30 
  ; 
  and 
  it 
  seemed 
  worth 
  

   trying 
  what 
  would 
  be 
  the 
  effect 
  of 
  omitting 
  these 
  and 
  all 
  above 
  four 
  

   times 
  the 
  probable 
  error 
  of 
  one. 
  In 
  this 
  case 
  for 
  W-W' 
  it 
  was 
  all 
  above 
  

   15. 
  The 
  result 
  is 
  that 
  2360 
  observations 
  give 
  0*0559, 
  showing 
  how 
  little 
  

   even 
  considerable 
  discordances 
  affect 
  a 
  mean 
  under 
  such 
  circumstances, 
  

   and 
  also 
  perhaps 
  that 
  even 
  such 
  discordances 
  should 
  not 
  be 
  rejected. 
  

  

  IX. 
  - 
  e 
  Preliminary 
  Notice 
  of 
  further 
  Researches 
  on 
  the 
  Physical 
  

   Properties 
  of 
  Matter 
  in 
  the 
  Liquid 
  and 
  Gaseous 
  States 
  under 
  

   varied 
  conditions 
  of 
  Pressure 
  and 
  Temperature." 
  By 
  Br. 
  

   Andrews, 
  F.B.S., 
  Vice-President 
  of 
  Queen's 
  College, 
  Belfast. 
  

   Received 
  June 
  17, 
  1875. 
  

   The 
  investigation 
  to 
  which 
  this 
  note 
  refers 
  has 
  occupied 
  me, 
  with 
  little 
  

   intermission, 
  since 
  my 
  former 
  communication 
  in 
  1869 
  to 
  the 
  Society, 
  " 
  On 
  

   the 
  Continuity 
  of 
  the 
  Liquid 
  and 
  Caseous 
  States 
  of 
  Matter." 
  It 
  was 
  un- 
  

   dertaken 
  chiefly 
  to 
  ascertain 
  the 
  modifications 
  which 
  the 
  three 
  great 
  laws 
  

   discovered 
  respectively 
  by 
  Boyle, 
  Gay-Lussac, 
  and 
  Dalton 
  undergo 
  when 
  

   matter 
  in 
  the 
  gaseous 
  state 
  is 
  placed 
  under 
  physical 
  conditions 
  differing 
  

   greatly 
  from 
  any 
  hitherto 
  within 
  the 
  reach 
  of 
  observation. 
  It 
  embraces 
  

   a 
  large 
  number 
  of 
  experiments 
  of 
  precision, 
  performed 
  at 
  different 
  tem- 
  

   peratures 
  and 
  at 
  pressures 
  ranging 
  from 
  twelve 
  to 
  nearly 
  three 
  hundred 
  

   atmospheres. 
  The 
  apparatus 
  employed 
  is, 
  in 
  all 
  its 
  essential 
  parts, 
  

   similar 
  to 
  that 
  described 
  in 
  the 
  paper 
  referred 
  to 
  ; 
  and 
  so 
  perfectly 
  did 
  

   it 
  act 
  that 
  the 
  readings 
  of 
  the 
  cathetometer, 
  at 
  the 
  highest 
  pressures 
  

   and 
  temperatures 
  employed, 
  were 
  made 
  with 
  the 
  same 
  ease 
  and 
  accuracy 
  

   as 
  if 
  the 
  object 
  of 
  the 
  experiment 
  had 
  been 
  merely 
  to 
  determine 
  the 
  

   tension 
  of 
  aqueous 
  vapour 
  in 
  a 
  barometer-tube. 
  In 
  using 
  it 
  the 
  chief 
  

   improvement 
  I 
  have 
  made 
  is 
  in 
  the 
  method 
  of 
  ascertaining 
  the 
  original 
  

   volumes 
  of 
  the 
  gases 
  before 
  compression, 
  which 
  can 
  now 
  be 
  known 
  

   w 
  T 
  ith 
  much 
  less 
  labour 
  and 
  greater 
  accuracy 
  than 
  by 
  the 
  method 
  I 
  

   formerly 
  described. 
  The 
  lower 
  ends 
  of 
  the 
  glass 
  tubes 
  containing 
  

   the 
  gases 
  dip 
  into 
  small 
  mercurial 
  reservoirs 
  formed 
  of 
  thin 
  glass 
  

   tubes, 
  which 
  rest 
  on 
  ledges 
  within 
  the 
  apparatus. 
  This 
  arrangement 
  

   has 
  prevented 
  many 
  failures 
  in 
  screwing 
  up 
  the 
  apparatus, 
  and 
  has 
  given 
  

   more 
  precision 
  to 
  the 
  measurements. 
  A 
  great 
  improvement 
  has 
  also 
  

   been 
  made 
  in 
  the 
  method 
  of 
  preparing 
  the 
  leather-washers 
  used 
  in 
  the 
  

   packing 
  for 
  the 
  fine 
  screws, 
  by 
  means 
  of 
  which 
  the 
  pressure 
  is 
  obtained. 
  

   It 
  consists 
  in 
  saturating 
  the 
  leather 
  with 
  grease 
  by 
  heating 
  it 
  in 
  vacuo 
  

  

  