8 
Several  Official  Ointment*. 
(Am.  Jour.  Pharm. 
I.       Jan.,  1886. 
also  happens  with  other  heavy  powders  when  mixed  with  petrolatum 
alone — a  partial  separation  occurs.  Stearic  acid,  when  here  added, 
produces  a  mercuric  stearate,  showing  that  its  presence  is  not  admissi- 
ble. When  mercuric  oxide  is  warmed  with  melted  stearic  acid,  com- 
bination quickly  and  effectually  takes  place  in  the  generation  of  a 
definite  mercuric  stearate.  .  This  substance  is  white,  crystalline,  and 
readily  fusible,  in  these  respects  differing  but  inappreciably  from 
stearic  acid.  It  is  somewhat  less  soluble  in  ordinary  fats  than  the 
acid.  When  warmed  with  certain  oils — as,  for  instance,  cotton-seed 
oil — metallic  mercury  is  promptly  liberated.  Its  solub'lity  in  warm 
petrolatum  and  petrolatum  oil  is  considerably  greater,  while  remain- 
ing absolutely  permanent  in  this  connection.  On  cooling,  these  solu- 
tions congeal  and  form  ointments  of  good  consistency,  but  of  somewhat 
irregular  grain.  If  suitable  solvents  and  media  can  be  found,  mer- 
curic stearate  will  doubtless  find  some  valuable  uses. 
The  addition  of  nitric  acid  to  a  congealing  mixture  of  mercuric 
stearate  and  petrolatum  decomposes  the  former;  and  as  the  stearic 
acid  is  much  more  soluble  in  the  medium  than  its  mercuric  salt,  an 
ointment  of  excellent  consistency  results.  The  writer  has  taken 
advantage  of  this  reaction  for  the  preparation  of  citrine  ointment. 
Nitric  acid  has  but  little,  if  any,  effect  when  warmed  with  pure  stearic 
acid,  and  scarcely  more  on  petrolatum. 
When  a  solution  of  mercuric  nitrate  is  mixed  with  a  congealing 
mixture  of  stearic  acid  and  petrolatum,  a  proper  merging  results,  and 
an  ointment  having  a  petrolatum  color  is  obtained.  If,  however,  the 
mixture  is  first  warmed  on  a  water  bath  for  a  short  time,  the  ointment 
becomes  of  a  lighter  yellow,  although  no  visible  reaction  occurs. 
Should  it  be  desirable  to  make  a  citrine  ointment  having  the  usual 
color  and  odor  of  this  preparation,  a  small  quantity  of  lard  previously 
heated  with  a  little  nitric  acid  may  be  mixed  with  the  petrolatum 
product.  The  writer  finds  an  advantage  in  the  use  of  mercuric  oxide 
for  producing  the  nitrate.  In  preparing  the  solution,  a  small  excess 
of  the  acid  is  used.  The  writer  recommends  the  following  formula 
for  making  ointment  of  mercuric  nitrate: 
Red  mercuric  oxide   1  troy  ounce. 
Nitric  acid   1 
Water  180  minims. 
Stearic  acid   3 h  troy  ounces. 
Petrolatum  KU-  " 
Mix  the  mercuric  oxide  with  the  water  and  gradually  add  the  nitric 
