402 
Examination  of  Butter. 
Am.  Jour.  Pharm. 
Aug.,  1885. 
centage  of  glycerin  contained  in  solutions  of  determined  specific  grav- 
ity, he  calculated  the  yield  in  glycerin  from  the  fat  treated.  This 
method  has  not,  so  far  as  the  author  is  aware,  been  adopted,  and  it  is 
doubtful  if  it  will  be.  First  of  all,  the  glycerin  obtained  is  impure, 
containing  compound  salts  of  glycerin  and  baryta.  For  this  reason 
the  results  are  liable  to  vary  with  the  different  fatty  bodies ;  the  gly- 
cerin of  each  different  fat  will  contain  proportions  of  saline  matters 
different  from  the  glycerin  yielded  by  the  fat  taken  as  a  type,  the  solu- 
tions of  which  have  been  regarded  as  containing  the  standard  amount 
of  glycerin.  Although  we  know  that  the  volumetric  determination  of 
glycerin,  or  more  properly  the  hydrometric  determination,  cannot  be 
used,  the  process  of  saponification  may  be  applied  with  advantage  to 
the  examination  of  butter.  We  shall  describe  the  method  as  it  might 
be  used  for  butter  analysis.  David's  paper  will  be  found  in  "  Comptes 
Rendus,"  1882. 
The  sample  of  butter,  so  called,  is  first  melted  in  the  air-bath  at 
70°C.  The  clear  fat  rising  above  the  water,  salt  and  other  impuri- 
ties, is  decanted  through  a  small  diy  filter,  placed  in  a  warm  funnel, 
and  the  filtrate  is  collected  in  a  small  dish.  About  20  grams  are 
taken,  allowed  to  cool,  and  weighed,  together  with  a  small  spatula. 
10  grams  are  removed  and  placed  in  a  porcelain  capsule  of  about  500 
cc,  heated  on  a  steam  or  water  bath,  and  when  the  fat  is  very  warm 
20  grams  of  barium  hydrate  (9  mols.  water)  are  added.  When  the 
emulsion  has  formed,  pour  in  30  cc.  of  hot  alcohol,  at  90° C,  stirring 
briskly  until  the  mass  is  nearly  dry. 
Add  200  cc.  of  cold  water ;  break  the  mass  of  barium  soap  with 
the  spatula,  and  boil  to  reduce  the  liquid  to  one-half.  Cool  for  a  time, 
decant  through  a  linen  filter,  repeating  the  boiling  and  the  decantation 
three  times  at  least ;  then,  finally,  throw  the  whole  contents  of  the 
capsule  upon  the  filter,  after  dividing  the  soap  finely  with  a  small  pestle. 
Wash  the  filter  with  a  few  cc.  of  water,  and  squeeze  it  with  the  fingers. 
Evaporate  all  of  the  solutions  to  about  100  cc. ;  add  litmus  and  neu- 
tralize cautiously  with  dilute  sulphuric  acid.  Neutralize  the  slight 
excess  of  acid  with  barium  carbonate  Filter  the  solution,  wash  the 
filter,  and  evaporate  the  liquor  to  a  syrupy  consistency. 
As  has  already  been  said,  the  glycerin  so  obtained  is  not  pure. 
Treat  the  contents  of  the  capsule  with  strong  alcohol ;  a  large  quantity 
of  salts  is  thrown  down.  The  alcoholic  solution  is  filtered  through  a 
small  filter,  previously  moistene:!  with  alcohol,  and  the  filtrate  is  col- 
