﻿392 
  Linebarger 
  — 
  Some 
  Relations 
  between 
  Temperature, 
  

  

  considerably 
  from 
  the 
  normal 
  average 
  value 
  in 
  the 
  case 
  of 
  the 
  

   acids, 
  nitro-methane 
  and 
  nitro-ethane, 
  the 
  alcohols, 
  acetone 
  and 
  

   water. 
  For 
  the 
  acids 
  and 
  nitrocompounds 
  they 
  are 
  too 
  small 
  ; 
  

   for 
  the 
  alcohols, 
  water, 
  and 
  acetone, 
  they 
  are 
  too 
  large. 
  The 
  

   cause 
  of 
  this 
  abnormal 
  behavior 
  is 
  to 
  be 
  found 
  in 
  the 
  " 
  associa- 
  

   tion" 
  of 
  the 
  molecules 
  of 
  these 
  liquids, 
  and 
  in 
  the 
  changes 
  

   which 
  the 
  molecular 
  aggregations 
  undergo 
  during 
  the 
  process 
  

   of 
  vaporization. 
  We 
  will 
  consider 
  the 
  case 
  of 
  the 
  alcohols, 
  

   water, 
  and 
  acetone 
  first. 
  

  

  The 
  brilliant 
  experiments 
  of 
  Eamsay 
  and 
  his 
  associates 
  on 
  

   the 
  surface 
  tensions 
  of 
  liquids, 
  and 
  his 
  theoretical 
  deductions 
  

   have 
  taught 
  us 
  that 
  the 
  liquids 
  in 
  question 
  are 
  made 
  up 
  of 
  

   molecules 
  in 
  a 
  state 
  of 
  association. 
  No 
  facts 
  are 
  known, 
  how- 
  

   ever, 
  which 
  indicate 
  that 
  an 
  appreciable 
  amount 
  of 
  molecular 
  

   association 
  is 
  persistent 
  in 
  the 
  vaporous 
  state 
  ; 
  on 
  the 
  contrary, 
  

   the 
  normality 
  of 
  the 
  vapor 
  density, 
  and 
  other 
  properties 
  of 
  the 
  

   vapors, 
  show 
  that 
  they 
  consist 
  exclusively, 
  it 
  may 
  be 
  said, 
  of 
  

   simple 
  molecules. 
  Accordingly, 
  when 
  the 
  alcohols, 
  etc., 
  are 
  

   evaporated, 
  there 
  occurs 
  a 
  decomposition 
  of 
  the 
  complex 
  mole- 
  

   cules 
  into 
  simple 
  ones. 
  This 
  requires 
  the 
  expenditure 
  of 
  a 
  

   certain 
  amount 
  of 
  energy, 
  which 
  is 
  manifest 
  as 
  heat 
  energy. 
  

   The 
  heat 
  necessary 
  to 
  convert 
  a 
  molecularly 
  polymerized 
  liquid 
  

   into 
  its 
  normal 
  vapor 
  consist 
  then 
  of 
  two 
  terms,* 
  the 
  heat 
  

   expended 
  in 
  actually 
  turning 
  the 
  liquid 
  into 
  a 
  gas, 
  and 
  the 
  heat 
  

   used 
  up 
  in 
  decomposing 
  the 
  molecular 
  aggregations 
  or 
  " 
  tag- 
  

   mas." 
  The 
  value 
  of 
  p, 
  then, 
  in 
  the 
  expression 
  Tp 
  — 
  const, 
  is 
  

  

  greater 
  for 
  associated 
  than 
  for 
  normal 
  liquids 
  ; 
  hence 
  the 
  value 
  

   of 
  the 
  " 
  constant 
  " 
  becomes 
  greater, 
  and, 
  indeed, 
  so 
  much 
  the 
  

   greater, 
  the 
  more 
  complex 
  the 
  liquid 
  molecule. 
  It 
  seems 
  at 
  

   present 
  impossible 
  to 
  make 
  a 
  reliable 
  correction 
  for 
  the 
  heat 
  

   employed 
  in 
  decomposing 
  the 
  complex 
  molecules. 
  

  

  In 
  the 
  case 
  of 
  the 
  acids, 
  the 
  state 
  of 
  affairs 
  is 
  somewhat 
  dif- 
  

   ferent. 
  It 
  has 
  long 
  been 
  known 
  that 
  the 
  organic 
  acids, 
  as 
  

   formic, 
  and 
  acetic 
  acid, 
  have 
  abnormal 
  vapor 
  densities 
  due 
  to 
  

   the 
  association 
  of 
  the 
  molecules 
  in 
  the 
  vaporous 
  state; 
  as 
  the 
  

   temperature 
  rises, 
  the 
  degree 
  of 
  association 
  becomes 
  less 
  and 
  

   less 
  until 
  the 
  normal 
  molecule 
  is 
  reached. 
  At 
  the 
  boiling 
  

   points 
  under 
  ordinary 
  atmospheric 
  pressure, 
  the 
  vapor 
  density 
  

   of 
  formic 
  acid 
  may 
  by 
  extrapolation 
  from 
  the 
  data 
  due 
  to 
  

   Petersen 
  and 
  Ekstrandf 
  be 
  put 
  at 
  2*5 
  at 
  100° 
  ; 
  this 
  multiplied 
  

   by 
  28*87 
  gives 
  a 
  molecular 
  mass 
  of 
  72 
  ; 
  and 
  this 
  value 
  of 
  p 
  

  

  when 
  introduced 
  into 
  the 
  relation 
  ^-— 
  = 
  const., 
  gives 
  for 
  the 
  

  

  1 
  abs 
  

  

  * 
  See 
  G-uye's 
  paper 
  : 
  Sur 
  la 
  polymirisation 
  mol6eulaire 
  des 
  liquides 
  : 
  Archives 
  

   des 
  Sciences 
  physiques 
  et 
  naturelles, 
  III, 
  xxxi, 
  160, 
  ] 
  894. 
  

   f 
  Ber. 
  der 
  deutschen 
  chem. 
  Gesell., 
  xiii, 
  1194. 
  

  

  