LIQUOR  FERRI  TERSULPHATIS. 
29 
gree  of  pertinacity.  But  from  having  been  applied  in  the 
writer's  practice  with  supposed  advantage,  they  are  given  to 
attract  thought  and  attention  to  the  subject  in  advance  of  the 
approaching  revision  of  the  Pharmacopoeia. 
As  illustrative  examples  of  such  an  application  in  practice 
the  formulae  of  the  following  paper  are  expressed  in  this  manner. 
OBSERVATIONS  UPON  SOME  FORMULAE  AND  PROCESSES  FOR 
PREPARATIONS  THAT  MAY  BE  BROUGHT  FORWARD  FOR  AD- 
MISSION  INTO  THE  PHARM ACOPCEl A. 
By  Edward  R.  Squibb,-  M.  D. 
In  point  of  importance,  utility  and  convenience  there  is  pro- 
bably no  preparation  that  could  be  introduced  into  the  Pharma- 
copoeia with  greater  advantage  than  a  well  adjusted  solution  of 
tersulphat^  of  sesquioxide  of  iron. 
Such  a  solution  should  always  be  kept  in  readiness  for  pre- 
paring the  antidote  to  arsenic,  and  might  with  great  advantage 
be  substituted  for  the  crystallized  sulphate  of  protoxide,  when- 
ever that  salt  is  used  in  formulae  for  preparations  of  the  sesqui- 
oxide, as  for  instance,  in  the  preparation  of  citrate  of  iron, 
tartrate  of  iron  and  potassa,  ferrocyanide  of  potassium,  hydrated 
oxide  of  iron,  and  for  preparations  not  officinal. 
Liquor  Ferri  Tersulphatis. 
Take  of  Sulphate  of  Iron,     one  hundred  and  thirty-nine  parts. 
=FeO,S03+  7HO,  or  one  equivalent. 
Sulphuric  Acid,      twenty-five  parts. 
=  S03+Aq.  or  half  an  equivalent. 
Nitric  Acid,  sixteen  parts. 
=  1  part  plus  the  equivalent  quantity. 
Distilled  water,  a  sufficient  quantity. 
To  forty-five  parts  of  the  water,  in  a  basin  of  the  capacity  of 
five  hundred  parts,  add  the  sulphuric  and  nitric  acids  and  heat 
the  mixture.  Then  add  the  sulphate  of  iron  in  portions  of  one- 
tenth  of  the  whole  quantity,  at  short  intervals,  with  stirring. 
When  the  whole  of  the  salt  shall  have  been  added,  boil  the 
solution  and  test  it  for  protoxide  by  means  of  solution  of  ferrid- 
cyanide  of  potassium.    Should  the  test  produce  a  blue  instead 
