122  Notes  on  Compound  Resorcinol  Ointment.  {AnMirch,imrm* 
One  other  point  should  be  spoken  of  in  connection  with  this 
ointment.  It  is  directed  in  the  N.F.  that  this  ointment  should  be 
protected  from  light.  The  change  of  color  which  occurs  is  quite 
striking  and  is  attributed  usually  to  the  resorcinol,  which,  as  a  phenol, 
becomes  pinkish,  as  is  recognized  in  the  Pharmacopoeia,  when 
exposed  to  light  and  air.  This  change  of  color  is  undoubtedly  due 
to  the  presence  of  this  phenol,  since  the  mixture  of  all  the  ingre- 
dients excepting  the  resorcinol  will  not  show  such  a  change,  but,  on 
the  other  hand,  if  the  ointment  be  prepared  to  the  point  of  adding 
the  oil  of  cade,  and  this  mixture  allowed  to  stand,  the  creamy  white 
color  is  not  noticeably  modified  by  exposure  to  either  light  or  air  for 
at  least  ten  days.  The  conclusion  which  must  be  drawn  is  that  the 
resorcinol  and  the  oil  of  cade  together  are  responsible  for  the  color 
changes.  To  a  sample  of  the  ointment,  completed,  excepting  the 
addition  of  the  oil  of  cade,  creosote  was  added.  There  is  no  change 
in  color. 
Acetic  acid  was  added  to  another  sample,  likewise  without  affect- 
ing the  color.  It  is  evident  that  some  other  principle  is  present  in 
the  oil  of  cade  to  cause  this  rapid  oxidation. 
These  color  changes  are  quite  striking.  The  ointment,  when  first 
prepared,  is  of  a  light,  reddish-brown  color.  Within  one-half  hour 
it  has  changed  to  a  gray-brown  on  the  surface  and  inside  of  one 
hour  it  develops  a  distinct,  pinkish  tint.  If  this  be  exposed  to  light 
and  air  for  twenty-four  hours,  it  has  assumed,  on  the  surface,  a  pur- 
plish color,  much  darker  than  at  first.  This  change  seems  to  be  due 
more  to  contact  with  air  than  to  light,  for  the  same  change  seems 
to  occur  in  an  ointment  kept  in  a  closed  ointment  jar,  although  the 
change  is  only  upon  the  surface  ;  the  ointment  one-eighth  of  an  inch 
below  the  surface  showing  no  purplish  color,  but  the  same  gray-brown 
which  it  had  assumed  soon  after  preparation.  It  has  been  suggested 
that  the  ointment  be  prepared,  excepting  the  addition  of  the  oil 
of  cade,  and  that  the  oil  of  cade  be  added  when  the  ointment  is 
dispensed.  This,  if  followed,  will  insure  a  uniform  product  when 
the  ointment  leaves  the  pharmacy. 
