380  Potassium  Iodide  and  Bromide.  {KmK^iYmlm' 
solely  for  the  purpose  of  demonstrating,  in  a  measure,  the  signifi- 
cance of  this  long-  known,  but  hitherto  not  w^//-known,  fact  to  phar- 
macy. Very  truly  yours, 
Wilbur  L.  Scoville. 
Boston,  Mass.,  July  13,  1894. 
POTASSIUM  IODIDE  AND  BROMIDE  OF  THE  MARKET- 
DO  THEY  COME  UP  TO  THE  REQUIREMENTS  OF  THE 
PHARM  ACOPCEIA  ? 
By  G.  H.  Chas.  KXie. 
Read  before  the  Missouri  Pharmaceutical  Association,  June,  1894. 
POTASSIUM  IODIDE. 
The  Pharmacopoeia  gives  the  following  tests  for  potassium  iodide : 
Solubility  of  a  given  quantity  of  the  salt  in  a  given  quantity  of 
dilute  alcohol,  specific  gravity  o  928. 
A  test  for  the  alkali  limit. 
The  salt  must  not  contain  sodium,  iodate,  sulphate,  arsenic,  lead, 
copper,  nitrate  or  nitrite,  iron,  cyanide.  The  purity  percentage, 
which  is  given  as  99*5  per  cent.,  is  determined  volumetrically. 
Twelve  samples  of  potassium  iodide  were  purchased  in  the  mar- 
ket. The  intention  was  to  examine  the  brands  used  in  the  United 
States  only. 
Except  three,  all  samples  were  granulated.  They  were  obtained 
from  eight  firms.  From  four,  two  samples  each,  and  from  four,  one 
each,  were  obtained. 
The  granulated  salt  was  chosen,  because  it  is  used  most.  As  a 
rule,  the  granulated  salt  is  not  as  pure  as  the  crystallized.  Crystal- 
lization will  exclude  many  impurities  which  remain  in  the  salt  when 
granulated. 
Sample  No.  1  was  not  as  soluble  as  the  test  demands ;  contained 
too  much  alkali.  It  also  contained  sodium  sulphate,  and  did  not 
show  the  purity  percentage  required. 
Sample  No.  2  contained  an  appreciable  amount  of  sulphate,  and 
did  not  come  up  to  the  standard  of  purity  percentage. 
No.  4  had  an  appreciable  quantity  of  sulphate  and  ammonia,  and 
could  not  be  placed  under  the  heading,  standard,  as  to  purity  per- 
centage. 
No.  5  contained  ammonia,  and  did  not  conform  to  the  standard 
ol  purity  percentage. 
