﻿Commissioner 
  of 
  Ageicultuke. 
  477 
  

  

  Livache's 
  Test. 
  

  

  The 
  power 
  possessed 
  by 
  linseed 
  oil 
  in 
  greater 
  measure 
  than 
  by 
  

   any 
  other 
  oil 
  to 
  absorb 
  oxygen 
  from 
  the 
  air, 
  and, 
  consequently, 
  to 
  

   increase 
  in 
  weight, 
  is 
  measured 
  by 
  Livache's 
  test, 
  Compt. 
  rend. 
  

   1895, 
  120, 
  812. 
  In 
  order 
  to 
  hasten 
  the 
  absorption 
  of 
  oxygen 
  a 
  

   weighed 
  quantity 
  of 
  the 
  oil 
  is 
  spread 
  out 
  in 
  a 
  thin 
  film 
  on 
  a 
  watch- 
  

   glass, 
  and 
  mixed 
  with 
  finely 
  divided 
  precipitated 
  metallic 
  lead. 
  

   At 
  the 
  end 
  of 
  each 
  2>eriod 
  of 
  12 
  or 
  24 
  hours 
  the 
  mixture 
  is 
  

   weighed, 
  and 
  the 
  increase 
  in 
  weight 
  noted. 
  The 
  amount 
  of 
  oxy- 
  

   gen 
  absorbed 
  in 
  this 
  way 
  by 
  oils 
  is 
  roughly 
  proportionial 
  to 
  the 
  

   absorption 
  of 
  bi'omine 
  and 
  iodine, 
  except 
  in 
  the 
  case 
  of 
  fish 
  oils. 
  

   Menhaden 
  oil, 
  though 
  having 
  a 
  power 
  to 
  absorb 
  bromine 
  or 
  iodine 
  

   but 
  slightly 
  inferior 
  to 
  that 
  of 
  linseed 
  oil, 
  falls 
  very 
  short 
  in 
  prac- 
  

   tical 
  diying 
  properties, 
  and 
  as 
  Livache's 
  test 
  oomes 
  nearer 
  than 
  any 
  

   other 
  to 
  an 
  actual 
  determination 
  of 
  the 
  real 
  drying 
  power 
  of 
  an 
  

   oil, 
  menhaden 
  oil 
  is 
  indicated 
  by 
  a 
  percentage 
  of 
  oxygen 
  that 
  is 
  

   proportionally 
  veiy 
  much 
  lower 
  than 
  that 
  of 
  linseed 
  oil, 
  than 
  the 
  

   bromine 
  or 
  iodine 
  figures 
  of 
  the 
  sample. 
  Details 
  of 
  the 
  process 
  will 
  

   be 
  found 
  in 
  Benedikt 
  and 
  in 
  Allen. 
  

  

  Livache 
  found 
  linseed 
  oil 
  to 
  gain 
  14.3 
  per 
  cent 
  of 
  its 
  weight 
  

   in 
  two 
  days, 
  while 
  Jean 
  (Monit. 
  Scient. 
  15, 
  891) 
  found 
  menhaden 
  

   oil 
  to 
  gain 
  only 
  5.454 
  per 
  cent 
  in 
  three 
  days. 
  

  

  Thus 
  if 
  an 
  oil 
  having 
  bromine 
  addition 
  figure 
  (after 
  allowing 
  for 
  

   the 
  effect 
  of 
  other 
  impurities 
  found), 
  that 
  is, 
  only 
  slightly 
  lower 
  than 
  

   that 
  of 
  lin=eed 
  oil, 
  strong 
  proof 
  is 
  had 
  of 
  the 
  presence 
  of 
  men- 
  

   haden 
  oil. 
  

  

  With 
  regard 
  to 
  other 
  adulterants 
  of 
  linseed 
  oil 
  the 
  test 
  does 
  not 
  

   furnish 
  information 
  at 
  all 
  comparable 
  in 
  value 
  with 
  that 
  obtained 
  

   by 
  determining 
  the 
  bromine 
  figures. 
  

  

  Index 
  of 
  Kefeaction. 
  

  

  "With 
  regard 
  to 
  the 
  index 
  of 
  refraction 
  the 
  difference 
  between 
  

   the 
  figures 
  of 
  linseed 
  oil 
  and 
  of 
  its 
  adulterants 
  is 
  comparatively 
  

   small, 
  and 
  much 
  less 
  work 
  has 
  been 
  done 
  in 
  this 
  direction 
  than 
  in 
  

   others. 
  The 
  following 
  figiu'es 
  are 
  taken 
  from 
  several 
  authorities: 
  

  

  