"""FirisS"" }  Syrup  of  Bromide  of  Zinc,  7  5 
acid  solution  of  ferric  chloride  answering  to  the  requirements  of  the 
Pharmacopoeia. 
Liquor  Ferri  Subsulphatis. — A  saturated  aqueous  solution  of  the  fer- 
rous sulphate  was  made,  and  to  it  the  sulphuric  acid  was  added  \  this 
solution  was  gradually  added  to  the  requisite  quantity  of  nitric  acid, 
both  the  acid  solution  of  ferrous  sulphate  and  the  nitric  acid  being  at 
76°F, ;  on  mixing,  the  solution  acquired  a  temperature  of  116'^F.,  and 
only  partial  oxidation  ensued,  leaving  a  dense  black  liquid  which,  on 
standing  two  days,  acquired  a  color  similar  to  the  officinal  liquor,  but 
contained  both  ferrous  and  ferric  sulphate  with  nitric  acid. 
Several  experiments  were  made,  using  each  time  an  increase  in  tem- 
perature, until  the  following  process  was  found  to  give  a  satisfactory 
result : 
Mix  the  nitric  and  sulphuric  acids  (using  a  slight  excess  of  nitric 
acid),  heat  them  to  I40°F. ;  make  a  hot  saturated  aqueous  solution  of 
ferrous  sulphate  (if  necessary  a  few  drops  of  sulphuric  acid  may  be 
added),  and  when  at  a  temperature  of  i8o°F.  or  igo^F.  filter  it  into 
the  heated  acids  ;  oxidation  takes  place  quietly  and  completely,  the 
nitrous  fumes  being  given  off  gradually  from  first  to  the  close  of  the 
operation.  After  oxidation  is  completed  the  solution  should  be  kept 
at  i4o°F.  for  a  few  minutes,  to  remove  all  traces  of  nitrous  fumes. 
The  result  is  a  solution  of  ferric  sulphate,  with  a  slight  trace  of  nitric 
acid. 
The  particular  advantage  of  these  formulas  is  that  there  is  no  accu- 
mulation  of  nitrous  fumes,  followed  by  their  sudden  expulsion  at  the  end 
of  the  oxidation,  causing  foaming  and  making  the  use  of  capacious 
dishes  a  necessity.  But  the  oxidation  and  liberation  of  the  nitrous 
fumes  takes  place  at  the  same  time,  from  the  first  gradually  to  the  close 
of  the  operation,  of  course  the  low  temperature  required  is  also  a 
marked  advantage. 
SYRUP  OF  BROMIDE  OF  ZINC. 
By  L.  Lyons. 
Read  at  the  Pharmaceutical  Meeting  January  20, 
The  processes  for  the  preparation  of  the  bromide  of  zinc  given  io 
the  chemical  text-books  are  based  upon  either  the  direct  combination 
of  zinc  with  bromine,  or  the  metal  is  dissolved  in  an  aqueous  solution 
of  hydrobromic  acid. 
