Arc.  Jour.  Pharm.  \ 
April,  1896.  J 
Laboratory  Notes. 
197 
wanting.  Some  of  the  best  manufacturers  maintain  that  the  official 
requirements  are  too  rigid  for  a  medicinal  product.  In  this  opinion 
the  writer  concurs  with  them  in  a  measure,  but  the  chemically  pure 
substance  certainly  ought  to  comply  with  these  requirements.  That 
the  Pharmacopoeia  is  practically  disregarded  in  the  manufacture  of 
this  chemical,  the  table  below  clearly  shows  : 
No. 
Alkalies. 
Sulphates. 
Iodates. 
Sodium. 
1 
Excess. 
Present. 
Absent. 
Absent. 
2 
Excess. 
Present. 
Present. 
Present. 
3 
Normal. 
Present. 
Absent. 
Absent. 
4 
Normal. 
Present. 
Absent. 
Absent. 
5 
Normal. 
Present. 
Absent. 
Present. 
6 
Normal. 
Absent. 
Absent. 
Present. 
7 
Normal. 
Absent. 
Present. 
Present. 
S 
Normal. 
Present. 
Absent. 
Present. 
9 
Excess. 
Present. 
Absent. 
Absent. 
10 
Excess. 
Present. 
Absent. 
Absent. 
11 
Excess. 
Present. 
Absent. 
Absent. 
12 
Normal. 
Absent. 
Present. 
Absent. 
A  trace  of  free  iodine  was  present  in  No  7.  No  other  impurities 
excepting  those  mentioned  in  the  table  above  were  present.  Even 
the  percent,  of  potassium  iodide  was  normal. 
The  writer  desires  to  call  attention  to  an  inconsistency  that  exists 
in  the  U.  S.  P.  requirements  for  testing  potassium  iodide.  A  limited 
amount  of  alkali  is  admissible.  This  alkali  is  always  present  as  a 
carbonate.  The  test  for  sulphates  reads  as  follows  :  "The  aqueous 
solution  should  remain  clear  after  the  addition  of  barium  chloride 
T.  S.  (absence  of  sulphates)." 
An  article  containing  the  limit  of  alkali  will  always  indicate  the 
presence  of  a  sulphate  under  these  conditions,  whether  the  latter  is 
present  or  not.  The  requirement  should  read  :  "  The  aqueous  solu- 
tion acidulated  with  hydrochloric  acid  should  not  be  rendered  turbid 
after  adding,  etc." 
REDUCED  IRON. 
In  examining  these  samples,  the  directions  of  the  Pharmacopoeia 
were  followed,  except  that  the  mixture  of  mercuric  chloride  and  iron 
were  heated  one  and  a  half  hours  instead  of  one  hour,  to  ensure  a 
