'^"De?'i8?2*™''}        ^^^^  History  of  Citrine  Ointment.  621 
The  Britisli  Pharmacopoeia  of  1864  gives  the  following  formula: 
Take  of 
Mercury,         ......         4  ounces. 
Nitric  acid,  sp.  gr.  1-5,     .         .         .         .         .     8  " 
Lard,  15  " 
Olive  oil,    .         .         .         .         .         .         .    32  " 
Dissolve  the  mercury  in  the  acid  with  the  aid  of  a  gentle  heat,  melt 
the  lard  in  tlie  oil,  by  a  steam  or  water-bath  in  a  porcelain  vessel 
capable  of  holding  six  times  the  quantity,  and  while  the  mixture  is  hot 
add  the  solution  of  mercury,  also  hot,  mixing  them  thoroughly ;  if  the 
mixture  does  not  froth  up  heat  till  this  occurs. 
The  B.  P.  of  1867  orders  12  ounces  of  nitric  acid,  sp.  gr.  1'42. 
This  formula  will  give  an  excellent  ointment,  and  when  complaints 
are  made  of  the  result  will  be  found  that  the  fault  is  in  the  operator, 
not  in  the  formula.  The  instructions  must  be  strictly  adhered  to,  or  a 
failure  will  probably  result,  and  especial  regard  must  be  paid  to  the 
temperature  af  which  the  mixture  is  made,  which  should  range  from 
180°  to  200°F.,  and  should  not  be  too  long  continued,  but  only  until  the 
ointment  froths  up  well  ;  if  large  quantities  be  made  the  temperature 
may  be  a  little  lower.  As  thus  prepared  it  is  of  a  fine  lemon-yellow 
■color,  and  keeps  for  a  fair  length  of  time,  perfectly  good. 
Such  are  the  varied  formulse  which  have  from  time  to  time  been 
given  to  this  interesting  ointment;  but  before  leaving  the  subject  I 
should  like  to  devote  a  short  notice  to  the  chemistry  of  the  prepara- 
tion. 
The  views  of  chemists  regarding  the  chemical  composition  of  the 
ointment  vary  considerably.  Evidently  the  original  idea  was  to  obtain 
an  ointment  of  mercuric  nitrate  ;  hence  the  name  given  to  it  in  the 
Pharmacopoeias.  But  this  was  entirely  a  failure,  for  on  adding  the 
acid  solution  of  nitrate  to  the  melted  lard  chemical  decomposition 
■occurs,  as  indicated  by  the  frothing.  Still,  this  was  considered  as 
simply  the  result  of  the  oxidation  of  the  fat  by  the  excess  of  acid ;  but 
Mr.  Schacht,  who  made  a  number  of  experiments  in  the  laboratories 
of  the  School  of  Pharmacy,  showed  that  the  ointment,  when  carefully 
prepared,  is  soluble  in  ether,  thus  indicating  that  the  mercury  exists  as 
some  compound  with  a  fatty  acid,  the  nitric  acid  in  combination  with 
the  mercury  being  in  some  way  retained  while  the  excess  is  evolved 
•during  effervescence.  In  M.  Schacht's  valuable  j)aper  (whic^li  will  be 
found  in  the     Pharmaceutical  Journal    [1],  vol.  iv,  p.  450,  he  also 
