﻿84 
  Mr. 
  Gervaise 
  Le 
  Bas 
  on 
  

  

  It 
  is 
  seen 
  from 
  the 
  above 
  table 
  that 
  a 
  contraction 
  of 
  about 
  

   15 
  is 
  observable 
  in 
  compounds 
  possessing 
  a 
  hexacyclic 
  ring. 
  

   Paraldehyde 
  C 
  G 
  H 
  12 
  3 
  , 
  which 
  is 
  a 
  fatty 
  derivative, 
  with 
  a 
  

   cyclic 
  structure, 
  also 
  manifests 
  a 
  similar 
  contraction 
  (15'8). 
  

   Certain 
  other 
  compounds, 
  such 
  as 
  thiophene, 
  pyrrol, 
  furfurla, 
  

   also 
  possess 
  a 
  very 
  marked 
  contraction, 
  that 
  is 
  one 
  of 
  about 
  

   11 
  units. 
  This 
  smaller 
  value 
  is 
  due 
  to 
  the 
  fact 
  that 
  the 
  com- 
  

   plexity 
  of 
  these 
  rings 
  is 
  less 
  than 
  those 
  given 
  in 
  the 
  above 
  

   table. 
  A 
  consideration 
  of 
  the 
  above 
  compounds 
  is 
  reserved 
  

   for 
  the 
  present. 
  

  

  Diamylene 
  C 
  10 
  H 
  20 
  may, 
  however, 
  be 
  mentioned 
  here. 
  

  

  Formula 
  : 
  CH 
  3 
  

  

  OH— 
  CH— 
  CH 
  2 
  CH 
  3 
  

  

  II 
  II 
  

  

  CH 
  3 
  CH 
  9 
  — 
  CH 
  — 
  CH 
  

  

  I 
  

   CH 
  3 
  

  

  V. 
  211*3, 
  W. 
  60, 
  n 
  x 
  3'7 
  222'0, 
  contraction 
  — 
  10'7. 
  

  

  This 
  case 
  of 
  diamylene, 
  as 
  well 
  as 
  that 
  of 
  paraldehyde, 
  is 
  a 
  

   striking 
  verification 
  of 
  the 
  idea 
  that 
  there 
  is 
  always 
  a 
  con- 
  

   traction 
  when 
  a 
  compound 
  possesses 
  cyclic 
  structure. 
  

  

  It 
  is 
  now 
  necessary 
  to 
  consider 
  rings 
  of 
  higher 
  complexity 
  

   than 
  that 
  of 
  benzene 
  for 
  instance 
  (Table 
  XXI. 
  p. 
  85). 
  

  

  The 
  last 
  compound 
  is 
  referred 
  to 
  in 
  Trans. 
  Chemical 
  Society, 
  

   1906, 
  cxi. 
  p. 
  312. 
  Camphor, 
  which 
  is 
  also 
  considered, 
  may 
  be 
  

   shown 
  to 
  be 
  subject 
  to 
  a 
  contraction 
  of 
  30*0 
  : 
  but 
  since 
  it 
  is 
  

   only 
  intended 
  to 
  deal 
  in 
  this 
  paper 
  with 
  those 
  compounds 
  

   which 
  follow 
  the 
  law 
  of 
  valency, 
  as 
  it 
  is 
  generally 
  understood, 
  

   a 
  number 
  of 
  ring 
  compounds 
  for 
  which 
  data 
  referred 
  to 
  the 
  

  

  I 
  boiling-point 
  exist 
  cannot 
  be 
  now 
  considered. 
  

  

  The 
  results 
  brought 
  out 
  by 
  Table 
  XXI. 
  show 
  unmistakably 
  

   that 
  not 
  only 
  is 
  there 
  a 
  special 
  contraction 
  when 
  a 
  com- 
  

   pound 
  possesses 
  ring-structure, 
  but 
  that 
  also 
  the 
  amount 
  of 
  

   the 
  contraction 
  is 
  a 
  function 
  of 
  the 
  complexity 
  of 
  the 
  ring. 
  

   The 
  above 
  compounds 
  which 
  are 
  distinguished 
  by 
  similar 
  ring- 
  

   structure 
  are 
  the 
  subjects 
  of 
  similar 
  contractions. 
  The 
  

   average 
  value 
  of 
  the 
  contraction 
  is 
  shewn 
  to 
  be 
  — 
  30*6. 
  It 
  

   is 
  remarkable 
  that 
  borneol, 
  and 
  of 
  course 
  camphor, 
  substances 
  

   which 
  have 
  only 
  recently 
  been 
  shown 
  to 
  possess 
  bridged 
  

   rings, 
  should 
  manifest 
  contractions 
  similar 
  to 
  those 
  of 
  naph- 
  

   thalene 
  or 
  quinolene, 
  which 
  are 
  bicyclic. 
  Camphene 
  would 
  

   no 
  doubt 
  manifest 
  a 
  similar 
  contraction. 
  

  

  