318  Analysis  of  Ointments.  {Amjfcmm 
as  far  as  possible,  and  the  extraction  repeated  with  another  portion 
of  chloroform.  The  chloroformic  solutions  are  collected  in  a  beaker 
and  exposed  to  a  gentle  heat  on  the  water  bath  until  the  chloroform 
is  completely  volatilized.  Morphine  is  only  very  slightly  soluble 
in  chloroform ;  it  can  be  extracted  with  a  mixture  of  equal  volumes 
of  ether  and  acetic  ether.  The  alkaloid  is  identified  by  the  usual 
method. 
Narcotic  Extracts. — In  the  presence  of  narcotic  extracts  or  if 
several  alkaloids  are  suspected,  also  when  considerable  organic  mat- 
ter soluble  in  the  acidulated  water  is  present,  it  is  advisable  to  resort 
to  Stas-Otto's  method  of  separating  the  alkaloid. 
Mineral  Oil,  Paraffin,  Vaselin,  Ceresin. — Five  grammes  of  the 
ointment  are  heated  with  25  c.c.  concentrated  sulphuric  acid  at  a 
temperature  of  1600  for  fifteen  minutes.  The  residue  is  intimately 
mixed  with  about  500  c.c.  water.  Vegetable  or  animal  fats  and  oils, 
resin  and  wax  are  carbonized,  any  mineral  oil,  paraffin,  vaselin,  etc., 
present  will  separate  on  the  surface  of  the  water. 
Another  method  is  based  on  their  indifference  to  alkalies  as  they 
can  not  be  saponified.  A  few  grammes  of  the  material  (admixtures 
of  water,  starch,  salts,  etc.,  must  be  removed  by  drying  and  filtra- 
tion) are  saponified  on  the  water  bath  in  an  Erlenmeyer  flask,  closed 
with  a  small  funnel,  with  a  4  per  cent,  alcoholic  potash  solution,  shak- 
ing frequently  to  assist  saponification.  The  mineral  oil,  paraffin  or 
vaselin  will  be  found  floating  in  drops  in  the  clear  liquid.  In  the 
presence  of  beeswax  the  saponification  should  be  carried  out  for  at 
least    one  hour. 
Substances  Soluble  in  Alcohol. — Certain  constituents  can  be  sepa- 
rated from  an  ointment  base  by  extracting  with  hot  alcohol,  filtering 
when  cool  and  evaporating  the  solvent.  Small  quantities  of  wax, 
fat,  oil,  vaselin,  lanolin,  etc.,  will  be  dissolved  at  the  same  time,  but 
not  sufficient  to  interfere  with  a  fairly  accurate  estimation  of  the 
alcohol  soluble  constituent,  provided  the  latter  is  present  in  not  too 
small  quantities.  Fatty  acids,  however,  are  more  readily  soluble 
in  alcohol  than  fats,  oils,  etc.  This  must  be  taken  in  consideration 
if,  for  example,  stearic  acid  is  found  to  be  present.  Substances 
soluble  in  alcohol  and  liable  to  be  constituents  of  an  ointment  are : 
resin,  turpentine,  balsam  of  Peru,  tar,  castor  oil,  croton  oil,  etc. 
Glacial  acetic  acid  in  place  of  alcohol  can  be  used  with  advantage 
as  a  solvent  in  some  cases.  After  the  alcohol  or  acetic  acid  has  been 
driven  off  on  the  water  bath,  the  material  left  behind  usually  can  be 
recognized  from  its  physical  appearance. 
