306 
Salicylates  of  Mercury. 
(  Am.  Jour.  Pharm 
(      June,  1882. 
•oxide  for  eacli  molecule  of  salicylic  acid.  But  in  practice  it  was  found 
that  with  these  proportions  in  the  presence  of  boiling  water  no  combi- 
nation takes  place,  and  the  yellow  tint  of  the  oxide  is  not  sensibly 
diminished.  If,  however,  without  interrupting  the  boiling,  a  fresh 
quantity  of  salicylic  acid  be  added,  the  yellow  tint  diminishes  and  dis- 
appears completely  when  a  second  molecule  of  acid  has  been  added. 
A  white  mass  is  obtained,  which,  upon  cooling  and  standing,  separates 
into  two  layers,  the  lower  very  dense  and  amorphous,  the  upper  crys- 
talline, and  consisting  of  interlaced  needles  of  salicylic  acid.  The 
whole  is  collected  on  a  filter  and  washed  with  boiling  Avater,  and  pre- 
ferably with  ether,  as  the  best  solvent  of  salicylic  acid,  until  the  ether 
no  longer  leaves  a  residue  upon  evaporating.  The  brilliant  white 
amorphous  matter  left  on  the  filter  has  the  composition  of  the  neutral 
mercuric  salicylate  as  above  indicated.  This  compound  is  insoluble  in 
water,  ether,  and  alcohol,  and  soluble  in  solution  of  sodium  chloride. 
It  dissolves  in  aqueous  solutions  of  potassium  iodide,  and  is  extremely 
soluble  in  potassium  cyanide.  If  a  current  of  sulphuretted  hydrogen 
be  passed  through  the  last-mentioned  solution,  the  liquid  at  length 
blackens  and  deposits  sulphide  of  mercury. 
Normal  mercuric  salicylate  is  obtained  by  precipitating  a  dilute  solu- 
tion of  salicylate  of  soda  in  excess  with  a  dilute  solution  of  mercuric 
nitrate.  The  white  precipitate  produced  is  collected  on  a  filter  and 
submitted  to  prolonged  washings  with  water,  to  remove  excess  of 
salicylate  of  soda  and  free  salicylic  acid,  until  the  wash  water  no 
longer  colors  ferric  chloride.  This  precipitate  presents  all  the  reactions 
of  the  mercuric  salts,  and  its  composition  corresponds  to  the  formula 
B.  Mercurous  Salicylates. — These  two  salts,  like  the  preceding, 
occur  in  the  amorphous  condition. 
Normal  mercurous  salicylate  is  obtained  by  double  decomposition  in 
precipitating  salicylate  of  soda  in  excess  with  a  solution,  as  slightly 
acid  as  possible,  of  mercurous  nitrate.  The  precipitate  can  be  washed 
with  boiling  water  without  fear  of  decomposition. 
Neutral  mercurous  salicylate  is  obtained  by  treating  the  normal  salt 
just  described  with  great  excess  of  ether,  when  it  breaks  up  into 
salicylic  acid,  which  remains  dissolved  in  the  ether,  and  neutral  mer- 
curous salicylate,  insoluble  in  ether  and  water.  The  ethereal  solution 
is  removed  by  decantation,  and  the  precipitate  is  washed  until  the  ether 
