﻿Optical 
  Rotativity 
  of 
  Solutions. 
  539 
  

  

  The 
  second 
  hypothesis 
  explains 
  the 
  variation 
  of 
  the 
  specific 
  

   rotativity 
  of 
  certain 
  substances 
  in 
  solution 
  by 
  

  

  2. 
  The 
  formation 
  of 
  molecular 
  aggregates. 
  — 
  Such 
  an 
  ex- 
  

   planation 
  has, 
  of 
  course, 
  been 
  experimentally 
  " 
  confirmed 
  " 
  

   for 
  certain 
  cases, 
  but 
  its 
  general 
  explanation 
  is 
  not 
  nearly 
  so 
  

   wide 
  or 
  even 
  so 
  well 
  supported 
  as 
  in 
  the 
  previous 
  case. 
  A 
  

   discussion 
  similar 
  to 
  that 
  given 
  above 
  will, 
  however, 
  show 
  

   that 
  this 
  process 
  has 
  probably 
  also 
  very 
  little 
  to 
  do 
  with 
  the 
  

   modifications 
  of 
  the 
  rotativity 
  of 
  the 
  dissolved 
  molecules. 
  

   The 
  few 
  facts 
  usually 
  explained 
  by 
  an 
  assumption 
  of 
  this 
  

   kind 
  are 
  all 
  involved 
  in 
  our 
  formula. 
  

  

  3. 
  Other 
  actions. 
  — 
  Similar 
  reasoning 
  will 
  also 
  dispose 
  of 
  

   any 
  probable 
  effect 
  due 
  to 
  other 
  actions 
  of 
  a 
  type 
  similar 
  to 
  

   those 
  just 
  discussed. 
  The 
  experimental 
  evidence 
  advanced 
  

   in 
  support 
  of 
  these 
  actions 
  does 
  not 
  appear 
  sufficiently 
  con- 
  

   clusive 
  to 
  enable 
  us 
  to 
  deny 
  the 
  actual 
  existence 
  of 
  these 
  

   effects; 
  but 
  as 
  all 
  the 
  experimental 
  results 
  appear 
  to 
  be 
  

   involved 
  in 
  the 
  present 
  theory 
  without 
  any 
  extensions, 
  we 
  

   may 
  conclude 
  that 
  their 
  action 
  is 
  at 
  least 
  small, 
  if 
  not 
  actually 
  

   non-existent. 
  

  

  Conclusion. 
  — 
  The 
  present 
  discussion 
  leaves 
  the 
  subject 
  in 
  

   a 
  very 
  unsatisfactory 
  state, 
  but 
  the 
  theory 
  points 
  the 
  way 
  

   for 
  the 
  future 
  experimental 
  investigations 
  which 
  may 
  help 
  

   us 
  to 
  more 
  definite 
  conclusions. 
  

  

  The 
  present 
  theory 
  explains 
  the 
  effects 
  by 
  the 
  variation 
  in 
  

   the 
  velocity 
  of 
  transmission 
  of 
  the 
  light-waves 
  in 
  the 
  solution. 
  

   Whether 
  this 
  theory 
  contains 
  a 
  complete 
  account 
  of 
  the 
  

   phenomena 
  is 
  uncertain, 
  but 
  it 
  can 
  be 
  tested. 
  As 
  I 
  have 
  

   before 
  pointed 
  out, 
  the 
  variation 
  caused 
  by 
  the 
  alteration 
  in 
  

   the 
  electrodynamic 
  conditions 
  under 
  which 
  the 
  typical 
  

   electon 
  vibrates, 
  and 
  which 
  govern 
  the 
  velocity 
  of 
  trans- 
  

   mission, 
  is 
  closely 
  allied 
  to 
  the 
  variation 
  of 
  the 
  index 
  of 
  

   refraction 
  of 
  the 
  medium, 
  and 
  a 
  formula 
  expressing 
  the 
  re- 
  

   lation 
  was 
  given. 
  A 
  measurement 
  of 
  the 
  refractive 
  index 
  

   in 
  each 
  experiment 
  would 
  thus 
  enable 
  us 
  to 
  determine 
  the 
  

   completeness 
  of 
  the 
  present 
  explanation. 
  

  

  If 
  it 
  is 
  found 
  that 
  the 
  variation 
  of 
  rotativity 
  is 
  not 
  com- 
  

   pletely 
  accounted 
  for 
  on 
  this 
  theory, 
  then 
  we 
  are 
  again 
  driven 
  

   to 
  account 
  for 
  the 
  departure 
  from 
  the 
  course 
  here 
  theoreti- 
  

   cally 
  discussed 
  by 
  assuming 
  a 
  definite 
  modification 
  in 
  the 
  

   chiral 
  group 
  in 
  the 
  molecule 
  produced 
  in 
  perhaps 
  diffe2'ent 
  

   degrees 
  by 
  the 
  different 
  circumstances 
  under 
  which 
  the 
  

   molecules 
  are 
  examined. 
  There 
  is 
  at 
  present, 
  however, 
  no 
  

   warrant 
  for 
  such 
  an 
  assumption, 
  but 
  I 
  hope 
  someone 
  will 
  

   take 
  up 
  the 
  question 
  and 
  provide 
  us 
  with 
  some 
  experimental 
  

   facts 
  to 
  argue 
  from. 
  

  

  