Am.  jour.  Pharm.  j     jjie  Stability  of  Iodine  Ointments. 
Aug.  19 1 7.       J  j  j 
343 
which  contain  fats  of  the  unsaturated  fatty  acid  series,  such  as  oleic 
acid,  do  not  satisfactorily  preserve  the  iodine  in  the  free  state.  In 
the  latter  class  it  seems  likely  that  the  iodine  enters  into  combination 
with  the  unsaturated  fatty  acids.  Accordingly,  on  theoretical 
groundsman  ointment  base  composed  of  pure  stearin  (if  such  sub- 
stance were  available)  but  softened  by  an  admixture  of  liquid 
petrolatum  would  preserve  the  iodine  satisfactorily.  Cocoanut  oil 
(iodine  No.  8)  ought  to  be  suitable  also  if  mixed  with  hard  paraffin. 
Since  the  literature  was  not  sufficiently  concordant  to  warrant 
positive  conclusions  concerning  the  stability  of  ointments  containing 
free  iodine,  it  seemed  worth  while  to  conduct  experiments  with 
preparations  of  known  origin.  Accordingly  a  number  of  prepara- 
tions containing  free  iodine  were  made  under  varying  conditions  and 
each  was  assayed  for  its  free  iodine  content  immediately  after  its 
manufacture  and  from  time  to  time  later. 
Leaf  lard  of  the  best  quality  obtainable  was  purchased  from  a 
butcher.  This  was  rendered  in  an  open  dish  on  the  steam  bath.  The 
preparation  was  of  a  fine  color,  and  uniform  consistence  and  had  a 
faint  but  not  unpleasant  odor.  Two  specimens  of  lard  were  fur- 
nished by  the  research  department  of  Armour  and  Company.  An 
effort  was  made  to  procure  specimens  of  lard  having  iodine  ab- 
sorption numbers  as  far  apart  as  possible,  i.  e.,  one  with  a  low  and 
the  other  with  a  high  iodine  value.  This  was  done  in  order  to  de- 
termine whether  the  keeping  qualities  of  the  ointments  prepared 
from  the  two  would  be  alike. 
One  of  the  specimens  (a)  was  described  as 
"Natural  lard;  iodine  value,  57.1.  Leaf  lard  used  exclusively  for  but- 
terine  and  benzoinated  lard." 
The  other  specimen  was  described  as 
"Prime  steam  lard.  Good,  commercial  grade  of  lard  for  general  use; 
iodine  value,  69.0." 
The  iodine  absorption  numbers  of  the  three  specimens  were  de- 
termined by  the  U.  S.  P.  process,  and  were  found  to  be  as  follows : 
Laboratory  rendered  specimen    57.1 
Armour  specimen  (a)    57.65 
,Armour  specimen  (b)    67.55 
Each  specimen  was  benzoinated  according  to  the  process  de- 
scribed in  the  U.  S.  P.  IX  and  100  Gm.  of  iodine  ointment  were  pre- 
