418     DETERMINATION  OF  TALLOW  OR  STEARIC  ACID  IN  WAX. 
fore,  necessary  to  discover  some  means  by  which  this  saponifia- 
ble  substance  might  be  separated  from  those  parts  of  the  wax 
which  can  not  be  saponified  by  carbonate  of  soda,  and  at  the 
same  time,  also,  from  the  tallow  and  stearic  acid.  I  found  that 
alcohol  answers  this  purpose ;  it  dissolves  this  saponifiable  sub- 
stance in  great  quantity,  whilst  the  dissolved  proportions  of  tal- 
low and  of  stearic  acid,  and  of  the  not  saponifiable  wax,  are  but 
very  inconsiderable. 
In  order,  therefore,  to  detect  an  adulteration  of  wax,  we 
must  first  examine  whether  it  be  adulterated  with  stearic  acid. 
For  this  purpose,  we  put  into  a  retort  about  two  drachms  of  the 
wax,  and  pour  over  it  one  ounce  of  limewater,  and  one  ounce  of 
distilled  water,  and  boil  for  some  time.  If  the  wax  does  actu- 
ally contain  stearic  acid,  the  liquid  completely  loses  every  trace  of 
alkaline  reaction.  This  fact  has  already  been  mentioned  by 
others,  but  with  the  addition  that  the  liquid  throws  down  a  pre- 
cipitate of  stearate  of  lime.  I  must,  however,  contradict  this 
observation,  for,  notwithstanding  repeated  experiments  which  I 
have  made,  I  was  not  able  to  discover  anything  of  the  kind.  I 
found,  moreover,  that  even  turbid  lime  water  became  clear, 
whether  boiled  with  pure  wax,  or  with  wax  adulterated  with 
either  tallow  or  stearic  acid,  but  it  did  not  lose  its  alkaline  reac- 
tion in  the  two  first  cases.  Lime  water  furnishes  us,  therefore, 
with  an  excellent  test  of  the  presence  of  stearic  acid  in  wax. 
It  is  also  useful  in  determining  the  quantity  of  stearic  acid  pre- 
sent ;  for  the  more  lime-water  of  constantly  equal  strength  is 
deprived  of  its  alkaline  reaction,  by  a  given  quantity  of  wax, 
adulterated  with  stearic  acid,  the  more  of  the  latter  must  the 
wax  contain. 
No  stearic  acid  having  been  detected,  the  wax  remains  yet  to 
be  tested  for  tallow,  which  is  done  in  the  following  way  : 
One  dram  of  wax  is  put  with  two  ounces  of  alcohol,  of  eighty 
per  cent.,  in  a  retort,  boiled  for  a  few  seconds,  and  the  whole 
quickly  poured  into  another  vessel,  which  contains  one  ounce  of 
cold  alcohol  of  eighty  per  cent.  The  retort  is  to  be  washed  out 
with  another  ounce  of  boiling  alcohol.  After  several  hours, 
when  quite  cold,  the  mixture  is  filtered,  and  two  ounces  more 
alcohol,  of  eighty  per  cent.,  poured  on  the  residue.  After  all 
the  alcohol  has  passed  through  the  filter,  the  latter  is  wrapped 
