6 
Several  Official  Ointments. 
Am.  Jour.  Pharm. 
Jan.,  18  6. 
whiteness.  The  ointment  is  then  best  prepared  by  melting  half  a 
troy  ounce  of  stearic  acid  with  half  a  troy  ounce  of  white  petrolatam, 
and  gradually  adding  five  troy  ounces  more  of  white  petrolatum  and 
setting  the  fused  mixture  aside.  One  troy  ounce  of  potassium  iodide 
and  eight  grains  of  sodium  hyposulphite  are  dissolved  in  one  fluid 
ounce  of  water.  This  solution  is  then  thoroughly  incorporated  with 
the  fatty  excipient,  either  before  or  after  complete  congelation  has 
occurred. 
Zinc  ointment,  when  prepared  with  lard  alone,  how  much  soever 
benzoinated,  will  soon  give  indications  of  change.  The  zinc  oxide 
seems  here  to  aid  in  decomposing  the  fat.  The  writer  is  in  the  habit 
of  preparing  considerable  of  this  ointment — usually  ten  pounds  at  a 
time.  A  small  proportion  of  white  wax  gave  very  good  results,  but 
subsequently  a  mixture  of  wax  and  spermaceti  proved  to  be  better. 
A  very  fine  product  is  obtained  by  the  use  of  stearic  acid.  In  this 
case  a  zinc  stearate  seems  to  form — at  least  superficially.  By  this 
means  the  ointment  has  a  much  finer  grain  than  usual,  while  the  zinc 
compound  remains  better  suspended  in  the  fused  excipient.  It  is 
questionable  whether  a  "preserved"  fat  is  essential  in  preparing  zinc 
ointment,  since  the  benzoic  or  cinnamic  acid  is  likely  to  combine  with 
the  zinc,  and  thus,  perhaps,  lose  its  efficiency.  Some  difficulty  is  en- 
countered in  preliminarily  giving  the  zinc  oxide  a  proper  degree  of 
fineness  for  admixture  with  the  fatty  medium.  For  a  long  time  the 
writer  secured  the  best  results  by  first  triturating  the  oxide  with  a 
small  proportion  of  the  fat,  and  then  gradually  adding  the  remainder 
in  a  melted  state.  Since  then  it  was,  however,  ascertained  that  when 
the  oxide  is  first  rubbed  together  with  a  small  proportion  of  powdered 
starch,  the  mixture  may  then  be  readily  passed  through  a  fine  sieve 
and  thus  brought  into  an  appropriate  form. 
The  following  process  has  thus  far  yielded  the  most  satisfactory 
product : 
Zinc  oxide   4  troy  ounces. 
Starch,  pulverized   \   "  " 
Spermaceti-   J   "  " 
White  wax   1  ' 
Lard   14  ' 
Balsam  tolu  120  grains. 
Triturate  the  oxide  of  zinc  with  about  three-fourths  of  the  powdered 
starch  and  sift  the  mixture  with  a  No.  80  sieve.  Rub  the  coarse 
portion  remaining  on  the  sieve  with  the  rest  of  the  starch,  and  pass  it 
