OINTMENT  OF  MERCURIC  NITRATE. 
417 
OINTMENT  OF  MERCURIC  NITRATE. 
By  R.  Rother. 
One  of  the  most  serious  imperfections  of  the  Pharmacopoeia 
IS  its  process  for  the  ointment  of  mercuric  nitrate.  This  is  a 
failure  in  every  respect,  the  nomenclature  not  excepted.  The 
ever-recurring  difficulties  that  the  officinal  formula  engenders 
have  caused  the  accumulation  of  abundant  literature  designed  to 
obviate  or  remove  some  of  these  inherent  obstacles.  But  even 
the  enumeration  of  all  the  known  processes  has  been  of  no  avail. 
Most  of  the  modifications  that  have  been  suggested  are  based 
upon  the  officinal  process  itself,  and  consist  mainly  of  alterations 
in  the  proportion  of  the  ingredients  or  their  quality.  But  the 
officinal  process  is  in  the  full  sense  of  the  term  irrational ;  like- 
wise must  be  any  other  which  grounds  itself  upon  this.  There- 
fore the  solution  of  this  profound  problem  cannot  be  discovered 
in  the  components  of  the  formula,  but  must  be  sought  for  in  the 
operation  alone.  A  review  of  all  the  known  facts  connected 
with  the  history  of  this  preparation  reveals  as  follows  ;  Firstly, 
since  the  value  of  this  combination  is  generally  recognized,  the 
title  should  be  distinctive  of  its  character.  In  this  regard  the 
Pharmacopoeia  completely  fails.  If  the  solution  of  the  metal  is 
officinally  effected  in  contact  with  the  acid  at  the  ordinary  tem- 
perature, it  is  positively  certain  that  both  mercuric  and  mer- 
curous  nitrate  form,  even  in  the  large  surplus  of  acid  shown  by 
the  precipitation  of  mercurous  chloride  in  the  presence  of  chlor- 
hydric  acid,  consequently  the  ointment  will  receive  both  nitrates 
from  the  beginning.  Evidently,  the  lower  the  temperature  at 
which  the  solution  is  made  the  greater  will  be  the  proportion  of 
mercurous  nitrate,  in  the  same  ratio  the  remaining  acid,  and 
through  it  the  more  powerful  the  oxidation  of  the  fats.  But  the 
intenser  the  reaction  the  more  probable  will  be  the  reduction  of 
the  mercurial  salts,  and  especially  the  mercurous  nitrate,  which 
is  eminently  dissimilar  in  its  effects  and  molecular  constitution 
to  the  mercuric  salt.  The  following  equations  will  sufficiently 
illustrate  the  above : 
3Hg-f8(N03H)=3(N03yig'')+N202+40H2 
6Hg  +  8(N03lI)-3(N03),Hg,)+N  A+40H, 
27 
