﻿Commissioner 
  of 
  Agriculture. 
  463 
  

  

  A 
  process 
  described 
  by 
  the 
  author 
  (J. 
  Amer. 
  Cliem. 
  Soc., 
  16, 
  56), 
  

   similar 
  to 
  one 
  used 
  previously 
  by 
  Allen 
  for 
  testing 
  sliale 
  oils, 
  dis- 
  

   tinguishes 
  lietween 
  addition 
  and 
  substitution, 
  and 
  by 
  its 
  use 
  the 
  

   presence 
  of 
  any 
  notable 
  amount 
  of 
  rosin, 
  rosin 
  oil, 
  or 
  mineral 
  oil 
  

   can 
  be 
  detected 
  with 
  a 
  considerable 
  degTee 
  of 
  accuracy, 
  and 
  a 
  

   fair 
  idea 
  formed 
  of 
  the 
  character 
  of 
  the 
  adulterant. 
  

  

  The 
  Hubl 
  is 
  one 
  of 
  the 
  best 
  kno\^^l 
  methods 
  of 
  fat 
  analysis; 
  the 
  

   method 
  by 
  -^vhich 
  the 
  Hubl 
  figures 
  were 
  obtained 
  for 
  tliis 
  report 
  

   was 
  as 
  follows: 
  

  

  A 
  solution 
  of 
  25 
  grams 
  of 
  iodine 
  and 
  30 
  gTams 
  of 
  mercuric 
  

   chloride 
  in 
  one 
  litre 
  of 
  alcohol 
  is 
  allowed 
  to 
  stand, 
  after 
  making, 
  for 
  

   twenty-four 
  houi-s 
  in 
  the 
  dark 
  before 
  using. 
  Two 
  hundred 
  milli- 
  

   gTams 
  or 
  thereabout 
  of 
  the 
  oil 
  to 
  be 
  analyzed 
  is 
  weighed 
  into 
  a 
  

   glass-stoppered 
  bottle, 
  10 
  c. 
  c. 
  of 
  chloroform 
  added 
  to 
  dissolve 
  the 
  

   oil, 
  and 
  25 
  c. 
  c. 
  of 
  the 
  iodine 
  solution 
  added. 
  If 
  the 
  solution, 
  when 
  

   shaken 
  to 
  mix 
  the 
  chloroform 
  and 
  alcoholic 
  liquid, 
  does 
  not 
  become 
  

   clear, 
  5 
  c. 
  c. 
  more 
  of 
  chloroform 
  is 
  added. 
  The 
  bottle 
  is 
  then 
  

   allowed 
  to 
  remain 
  in 
  the 
  dark 
  eighteen 
  horn's, 
  and 
  at 
  the 
  end 
  of 
  

   that 
  time 
  a 
  solution 
  of 
  ix)tassium 
  iodide 
  is 
  added, 
  and 
  the 
  free 
  

   iodine 
  in 
  the 
  s<jlution 
  titrated 
  with 
  tenth-normal 
  sodium 
  thio- 
  

   sulphate. 
  Twenty-five 
  c. 
  c. 
  of 
  the 
  same 
  iodine 
  solution 
  which 
  

   has 
  been 
  placed 
  in 
  a 
  similar 
  bottle 
  and 
  allowed 
  to 
  stand 
  with 
  the 
  

   test 
  is 
  titrated 
  at 
  the 
  same 
  time 
  \nth 
  thiosulphate, 
  and 
  the 
  differ- 
  

   ence 
  between 
  the 
  two 
  titrations 
  gives 
  the 
  amount 
  of 
  iodine 
  ab- 
  

   sorbed 
  by 
  the 
  oil. 
  Full 
  discussions 
  of 
  the 
  process 
  are 
  given 
  in 
  

   Benedikt, 
  Analyse 
  der 
  Fette 
  imd 
  Wachsarten, 
  and 
  in 
  Allen, 
  Com- 
  

   mercial 
  Organic 
  ^\jialysis. 
  

  

  The 
  bromine 
  figures 
  were 
  obtained 
  by 
  a 
  modification 
  of 
  the 
  

   author's 
  original 
  method. 
  The 
  method 
  actually 
  used 
  was 
  as 
  follows: 
  

  

  About 
  200 
  milligrams 
  of 
  the 
  oil 
  was 
  placed 
  in 
  a 
  dry 
  glass-stop- 
  

   pered 
  bottle, 
  10 
  c. 
  c. 
  of 
  carbon 
  tetrachloride 
  added 
  to 
  dissolve 
  the 
  

   oil, 
  and 
  then 
  20 
  c. 
  c. 
  of 
  third-normal 
  bromine 
  in 
  carl>on 
  tetra- 
  

   chloride 
  run 
  in 
  from 
  a 
  pipette. 
  Another 
  pipetteful 
  is 
  run 
  into 
  

   another 
  similar 
  bottle. 
  It 
  is 
  convenient, 
  but 
  not 
  absolutely 
  neces- 
  

   sary, 
  that 
  both 
  bottles 
  should 
  now 
  l>e 
  cooled 
  by 
  immersing 
  them 
  

  

  