﻿480 
  

  

  Seventh 
  Annual 
  Keport 
  of 
  the 
  

  

  5. 
  Rosin. 
  Indicated 
  by 
  high 
  specific 
  gravity, 
  high 
  bromine 
  ab- 
  

   sorption, 
  low 
  bromine 
  addition 
  figure, 
  high 
  bromine 
  substitution 
  

   figure, 
  and 
  when 
  in 
  the 
  free 
  state 
  by 
  high 
  acid 
  figure. 
  Separated 
  

   and 
  weighed 
  or 
  titrated 
  by 
  Twitchell's 
  process, 
  J. 
  Soc. 
  Chem. 
  Ind. 
  

   1891, 
  10, 
  804. 
  It 
  is 
  carried 
  out 
  by 
  treating 
  the 
  mixed 
  fatty 
  and 
  

   rosin 
  acids 
  obtained 
  by 
  acidifying 
  the 
  soap 
  solution 
  after 
  extraction 
  

   with 
  ether 
  in 
  the 
  determination 
  of 
  unsaponifiable 
  matter, 
  with 
  hy- 
  

   drochloric 
  gas 
  in 
  absolute 
  alcohol 
  solution. 
  By 
  this 
  treatment 
  the 
  

   fatty 
  acids 
  are 
  converted 
  into 
  ethyl 
  esters, 
  while 
  the 
  rosin 
  acids 
  are 
  

   not. 
  The 
  products 
  of 
  the 
  reaction 
  are 
  boiled 
  with 
  water, 
  the 
  

   mixed 
  fatty 
  acid 
  esters 
  and 
  rosin 
  separated 
  and 
  dissolved 
  in 
  naph- 
  

   tha. 
  From 
  this 
  solution 
  the 
  rosin 
  is 
  extracted 
  by 
  potassium 
  hy- 
  

   drate 
  solution. 
  The 
  rosin 
  soap 
  solution 
  is 
  treated 
  with 
  acid 
  and 
  

   the 
  liberated 
  rosin 
  weighed. 
  For 
  full 
  details 
  Allen's 
  Comm. 
  Org. 
  

   Anal. 
  (3d 
  ed.) 
  should 
  be 
  consulted. 
  

  

  Gladding's 
  method, 
  Amer. 
  Cbem. 
  J. 
  3, 
  416, 
  formerly 
  much 
  used, 
  

   for 
  the 
  determination 
  of 
  rosin, 
  depends 
  upon 
  the 
  solubility 
  of 
  silver 
  

   resinate 
  in 
  ether, 
  while 
  the 
  silver 
  salts 
  of 
  fatty 
  acids 
  are 
  soluble. 
  

  

  6. 
  Menhaden 
  oil. 
  Indicated 
  by 
  a 
  bromine 
  addition 
  figure 
  

   slightly 
  lower 
  than 
  that 
  of 
  linseed 
  oil, 
  but 
  a 
  higher 
  Maumene 
  figure 
  

   and 
  a 
  very 
  much 
  lower 
  figure 
  by 
  Livache's 
  test. 
  Indicated 
  also 
  

   by 
  characteristic 
  taste 
  and 
  odor. 
  

  

  T. 
  Corn 
  and 
  cottonseed 
  oils. 
  Indicated 
  by 
  low 
  specific 
  gravity, 
  

   low 
  bromine 
  absorption 
  and 
  low 
  bromine 
  addition 
  figure. 
  

  

  Table 
  showing 
  the 
  effects 
  of 
  temperature 
  upon 
  the 
  specific 
  gravity 
  

   of 
  linseed 
  oil.' 
  In 
  all 
  cases 
  water 
  at 
  15.5° 
  C. 
  taken, 
  as 
  unity. 
  

  

  