Am.  Jour.  Pharm. ) 
June,  1882.  / 
Salicylates  of  Mercury. 
305 
CgH^  I  Q^j^   or  CgH^  I  ^^^W    These  salts  are  not  very  stable, 
and  are  converted  by  carbonic  acid  into  normal  salts. 
Applying  these  theories  to  the  salicylates  of  mercury,  it  will  be  seen 
that  the  existence  is  possible  of  two  mercuric  and  two  mercurous 
salicylates. 
A.  Mercuric  Salicylates. — The  first  idea  that  presents  itself  for  the 
preparation  of  the  mercuric  salicylates  is  to  try  the  action  of  salicylate 
of  silver  upon  mercuric  chloride.  But  this  process  is  impracticable 
because  of  the  insolubility  of  the  salicylates  which  cannot  be  separated 
from  the  chloride  of  silver.  It  was  therefore  attempted  to  prepare  the 
mercuric  salicylate  by  double  decomposition,  in  allowing  a  molecule 
of  normal  salicylate  of  soda  to  react  upon  a  boiling  solution  of  mercuric 
chloride.  Upon  cooling,  a  relatively  not  very  abundant  amorphous 
white  precipitate  is  produced  (about  3  grams  for  13*5  grams  of  mercuric 
chloride).  Reagents,  however,  and  even  sulphuretted  hydrogen,  do 
not  give  any  indication  of  a  trace  of  mercury  in  the  liquid,  which  is 
acid.  In  this  compound  the  mercury  combined  with  the  salicylic 
acid  is  completely  disguised.  In  order  to  detect  it  by  the  wet  way,  it 
is  necessary  to  heat  slightly  the  salicylate  with  concentrated  sulphuric 
acid  until  it  becomes  flesh-colored,  and  then  add  water;  the  whole 
dissolves,  the  liquid  becoming  decolorized.  The  mercury  can  then 
be  detected  in  the  solution  by  the  ordinary  reagents.  Analysis  of 
this  precipitate  showed  that  it  consists  of  the  neutral  salicylate: 
f  CO  \ 
CgH^I  Q  2  ^  Hg'^    This  formula  explains,  up  to  a  certain  point  the 
disguising;  of  the  mercury,  the  biatomic  Hg^^  serving  as  a  link  between 
the  oxygen  and  the  group  CO2. 
The  neutral  mercuric  salicylate  is  soluble  in  solution  of  sodium 
chloride,  and  this  explains  the  relatively  small  amount  of  precipitate 
above  referred  to;  the  remainder  of  the  salicylate  being  held  in  solu- 
tion by  the  sodium  chloride  formed  on  the  reaction.  The  acidity  of 
the  liquid  is  due  to  free  salicylic  acid. 
The  reaction  is  very  interesting  from  a  theoretic  2>oint  of  view, 
since  it  shows  that  the  neutral  salicylate  is  more  stable  than  the  nor- 
mal salicylate. 
The  preceding  process  not  being  found  suitable,  the  authors  tried 
the  reaction  of  salicylic  acid  upon  yellow  oxide  of  mercury.  According 
to  theory  it  would  be  necessary  to  employ  a  molecule  of  mercuric 
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