Am.  Jour.  Pharm.  ) 
May,  1910.  / 
Ammoniated  Mercury. 
223 
THE  ASSAY  OF  OINTMENT  OF  AMMONIATED 
MERCURY. 
By  John  R.  Rippetoe. 
Determining  the  ammoniated  mercury  by  extracting  the  fats  by 
means  of  a  volatile  solvent  and  collecting  the  insoluble  residue  of 
this  salt  on  balanced  filters,  or  a  Gooch  crucible,  proved  to  be  very 
tedious  and  besides  it  was  impossible  to  obtain  a  result  that  was 
even  approximate.  Ether,  petroleum  ether,  and  chloroform  were  the 
solvents  used.  Several  filter  papers  of  fine  texture  were  used,  but 
none  of  them  seemed  to  be  of  such  a  character  as  to  prevent  some  of 
the  ammoniated  mercury  from  being  carried  through.  Extraction 
of  the  fats  by  means  of  a  Soxhlet  apparatus,  using  an  extraction 
tube,  was  even  less  satisfactory. 
Hence  the  following  method  was  worked  out  which  so  far  has 
given  very  satisfactory  results.  Weigh  accurately  2.5  to  3.0 
grammes  of  the  sample  into  a  four-ounce,  wide-mouthed  Erlenmeyer 
flask.  Add  50  c.c.  ether  and  dissolve  the  fats  by  agitation,  then 
add  10  c.c.  hydrochloric  acid  (10  per  cent.)  and  10  c.c' distilled 
water,  and  dissolve  the  ammoniated  mercury  by  agitation.  Trans- 
fer the  solutions  to  a  separator  and  draw  off  the  acid  solution. 
Wash  the  flask  and  separator  with  water  until  the  washings  give 
no  test  with  silver  nitrate  solution  for  chlorides.  Pass  hydrogen 
sulphide  into  the  combined  acid  solution  and  washings  until  satu- 
rated, and  set  aside  for  15  minutes  in  a  warm  place.  Collect  the 
mercuric  sulphide  on  balanced  filters  or  a  Gooch  crucible,  wash 
thoroughly  with  water,  and  dry  to  a  constant  weight  at  ioo°  C. 
The  weight  of  mercuric  sulphide  obtained  multiplied  by  1.0837 
equals  the  weight  of  ammoniated  mercury  in  the  sample  taken. 
Working  with  a  known  amount  of  ammoniated  mercury  incorporated 
with  the  same  proportion  of  white  petrolatum  and  hydrous  wool  fat, 
as  in  the  official  ointment,  99.1  per  cent,  of  the  salt  taken  was 
determined,  assuming  the  salt  to  have  been  100  per  cent.  pure. 
The  above  method  should  be  equally  applicable  for  the  assay  of 
the  ointments  of  mercuric  nitrate,  and  yellow  and  red  mercuric 
oxide. 
It  would  seem  desirable  that  the  next  revision  of  the  U.  S. 
Pharmacopoeia  should  have  some  such  method  of  assay  for  the 
above  ointments,  since  the  present  one  gives  a  method  of  assay  for 
mercurial  ointment. 
Analytical  Department, 
Schieffelin  &  Co.,  New  York. 
