^""■oS^'isS!'""'}        Petrolatum  in  the  Officinal  Ointments.  491 
better  ointment  may  be  made,  however,  by  digesting  the  mixture  in  a 
water-bath  and  stirring  thoroughly  as  it  cools. 
Unguentum  Diachylon. — Diachylon  Ointment. — Lead  plaster 
sixty  parts,  petrolatum  thirty-nine  parts,  oil  of  lavender  one  part; 
melt  together  the  lead  plaster  and  petrolatum  at  a  moderate  heat ;  then, 
having  permitted  the  mass  to  become  partly  cool,  incorporate  with  it 
the  oil  of  lavender,  and  stir  constantly  until  cold.  This  ointment  is  a 
decided  improvement  on  the  officinal  formula,  it  keeps  much  better, 
does  not  separate,  and  is  not  so  adhesive.  On  account  of  the  want  of 
uniformity  in  the  quality  of  olive  oil  permitted  by  the  Pharmacopoeia, 
physicians  often  complain  of  the  irritant  effects  produced  by  the  use 
of  this  ointment  as  ordinarily  dispensed.  The  use  of  petrolatum 
would  undoubtedly  do  away  with  these  difficulties,  and  a  smooth,  non- 
irritating  and  more  permanent  ointment  than  the  officinal  be  produced. 
Unguentum  Galeae. — Nutgall  Ointment. — Nutgall  in  No.  80 
powder  ten  parts,  petrolatum  ninety  parts.  Rub  the  nutgall,  with  the 
petrolatum,  gradually  added,  until  they  are  thoroughly  mixed.  For 
therapeutical  reasons  this  is  preferable  to  the  officinal. 
Unguentum  Hydrargyri. — Mercurial  Ointment. — Mercury  four 
hundred  and  fifty  parts,  petrolatum  three  hundred  parts,  yellow  wax 
one  hundred  and  fifty  parts,  compound  tincture  of  benzoin  forty  parts, 
mercurial  ointment  one  hundred  parts.  Mix  the  mercury  with  the 
tincture  of  benzoin  in  a  mortar,  add  the  mercurial  ointment  (which 
should  contain  fifty  per  cent,  of  mercury) ;  and  triturate  the  mixture 
until  globules  of  mercury  cease  to  be  visible ;  then  add  the  petrolatum 
and  yellow  wax,  previously  melted  together  and  partially  cooled,  and 
continue  the  trituration  until  globules  of  mercury  cease  to  be  visible 
under  a  magnifying  power  of  ten  diameters.  This  is  believed  to  be  a 
better  ointment  than  the  officinal,  for  both  lard  and  suet  are  dispensed 
with,  the  necessary  firmness  being  imparted  by  yellow  wax ;  the  pro- 
cess is  practically  more  rapid  than  the  officinal  because  suet  is  almost 
granular  in  its  character,  and  prolonged  trituration  is  necessary  to  break 
down  the  granules ;  the  disagreeable  odor  always  present  in  suet,  is  of 
course  absent  in  the  improved  preparation,  whilst  rancidity  is  effectu- 
ally prevented. 
Unguentum  Hydrargyri  Ammoniati. — Ointment  of  ammoniated 
Mercury. — Ammoniated  mercury,  in  very  fine  powder,  ten  parts,  petro- 
latum ninety  parts.    Rub  the  ammoniated  mercury  with  the  petro- 
