586  Preparing  Pharmaceutic  Chemicals.     fAm-  Jour-  Pharm- 
December,  1908. 
The  bismuth  salicylate  with  40%Bi203  is  as  shown  by  the  formulas 
not  a  definite  compound,  although  the  composition  comes  near  to 
that  of  bismuth  trisalicylate.  After  washing  the  bismuth  trisalicylate 
with  cold  water  until  free  from  ammonium  nitrate,  an  analysis  will 
show  if  the  product  has  to  be  further  washed  with  hot  water,  or  if 
salicylic  acid  should  be  added  in  order  to  obtain  a  salicylate  with 
an  ignition  residue  of  40%Bi203. 
ZINC  PERMANGANATE. 
This  is  not  an  official  preparation  and  its  medicinal  use  is  rather 
limited.  No  doubt  the  salt  is  a  very  good  antiseptic  and  astringent 
and  the  publication  of  a  cheap  practical  method  for  its  preparation 
may  therefore  be  of  interest. 
The  National  Dispensatory  states  that  this  salt  may  be  made  by 
exact  precipitation  of  barium  permanganate  with  zinc  sulphate,  but 
the  barium  salt  is  an  expensive  article,  making  the  method  imprac- 
ticable unless  it  can  be  cheaply  prepared.  The  author  has  manu- 
factured a  considerable  quantity  of  zinc  permanganate  by  the 
following  process : 
To  a  saturated  solution  of  potassium  permanganate  the  equivalent 
quantity  of  a  concentrated  silver  nitrate  solution  is  added.  Sparingly 
soluble  silver  permanganate  is  precipitated  at  once  according  to  the 
equation : 
KMn04  +  AgN03  =  AgMn04  +  KNOs 
The  mixture  is  kept  cold  by  addition  of  ice  and  left  standing  for 
a  couple  of  hours  to  make  the  precipitation  as  complete  as  possible, 
after  which  the  silver  permanganate  is  filtered  (preferably  using  a 
suction  pump  and  berliner  funnel)  and  washed  with  cold  water 
until  free  from  potassium  nitrate.  The  pure  silver  salt  is  then 
dried  below  ioo°  C.  The  yield  is  about  80  per  cent,  of  the  theoretical 
quantity.  To  the  washings  which  contain  the  rest  of  the  silver, 
sodium  chloride  is  added  and  the  precipitated  silver  chloride  collected 
by  filtration. 
The  dry  silver  permanganate  is  accurately  weighed,  transferred 
to  an  evaporating  dish,  5  to  8  times  its  weight  of  water  added,  and 
heated  on  a  steam  bath.  To  this  the  exactly  equivalent  quantity  of 
pure  zinc  chloride  is  added  and  the  whole  heated  with  frequent 
stirring  for  a  couple  of  hours. 
The  reaction  is  as  follows : 
2AgMn04  +  ZnCl2  =  Zn(Mn04)2  +  2AgCl 
