DETERMINATION  OP  TALLOW  OR  STEARIC  ACID  IN  WAX.  419 
up  in  a  few  sheets  of  filtering  paper,  and  pressed  between  two 
bricks  until  it  no  longer  appears  moist.  The  wax  is  now  placed 
in  a  porcelain  capsule,  with  one  dram  of  carbonate  of  soda  and 
six  drams  of  distilled  water,  and  boiled  until  the  bottom  of  the 
cup  begins  to  be  covered  with  carbonate  of  soda,  constantly 
stirring  it  with  a  glass  rod.  One  ounce  of  alcohol,  of  eighty 
per  cent.,  is  then  to  be  added  to  the  hot  mass,  and  the  whole 
rubbed  down  with  a  pestle,  until  the  undissolved  parts  form  a 
fine  powder ;  while,  at  the  same  time,  a  few  ounces  of  alcohol, 
of  fifty  per  cent.,  are  gradually  added.  When  cold,  the  whole 
quantity  is  carefully  filtered  and  washed  with  alcohol,  of  fifty 
per  cent.,  as  long  as  the  filtered  liquid  is  rendered  turbid,  by  a 
solution  of  neutral  acetate  of  lead  with  acetic  acid. 
The  whole  filtered  liquid  is  now  to  be  reduced  by  evaporation 
in  a  porcelain  capsule  to  one  ounce,  and  when  perfectly  cold, 
again  filtered,  and  the  residue  washed  with  water  mixed  with 
alcohol,  as  long  as  the  washings  are  rendered  turbid  by  a  solu- 
tion of  acetate  of  lead,  acidified  by  acetic  acid. 
Having  thus  obtained  about  two  ounces  of  liquid,  it  is  to  be 
poured  into  a  medicine  bottle,  and  well  shaken ;  if  the  wax  was 
pure,  a  slight  froth  will  form,  but  will  disappear  after  a  few 
minutes ;  if,  however,  it  was  adulterated,  with,  even  only  to  the 
extent  of  from  two  to  four  per  cent.,  tallow  or  stearic  acid,  a 
very  abundant  froth  forms  itself,  which  does  not  disappear  until 
after  half  or  one  hour. 
Another  test  may  now  be  made,  by  adding  to  the  liquid  in  the 
bottle  an  excess  of  acetic  acid.  If  the  wax  was  pure,  the  liquid 
will,  at  the  most,  become  scarcely  perceptibly  opalescent,  but 
not  distinctly  turbid.  If  it  contains,  however,  tallow  or  stearic 
acid,  a  more  or  less  abundant  flakey  precipitate  will  be  formed 
after  a  short  time,  particularly  if  the  bottle  be  shaken.  Grad- 
ually these  flakes  rise  to  the  surface  of  the  liquid.  If  it  is  de- 
sired to  determine  the  quantity  of  tallow  or  stearic  acid  present, 
the  liquid  is  not  to  be  mixed  with  acetic  acid,  but  is  to  be  treated 
in  the  following  manner  :  Add  to  it  a  solution  of  acetate  of  lead 
as  long  as  a  precipitate  falls  down,  then  add  acetic  acid  until 
the  liquid  acquires  a  distinct  acid  reaction.  The  precipitate  is 
to  be  allowed  to  fall  down,  for  several  hours,  then  placed  on  a 
filter,  weighed,  dried  in  a  temperature  of  212Q  Fahr.,  and  washed 
