368 
Bromide  of  Potassium. 
[Am.  Jour.  Pharm. 
X      August,  1904. 
I  do  not,  at  this  time,  discuss  the  minimum  requirements  for 
graduation.  That  is  a  very  large  subject,  and  is  still  more  difficult 
to  deal  with  than  the  matter  of  preliminary  education.  Even  the 
medical  and  dental  colleges,  with  all  their  years  of  experience,  have 
only  recently  come  to  a  general  agreement  as  to  length  of  time  to 
be  consumed  in  a  college  course,  and,  at  present,  I  am  not  prepared 
to  discuss  this  subject,  because,  in  my  judgment,  the  two  matters 
can  be  best  discussed  separately. 
BROMIDE  OF  POTASSIUM. 
By  Francis  J.  Smith. 
During  the  past  eighteen  months  the  writer  has  had  occasion  to 
examine  a  considerable  number  of  samples  of  bromide  of  potassium, 
and,  as  a  comparison  of  the  quality  of  different  manufacturers'  goods 
over  such  an  extended  period  may  be  of  interest,  it  has  been  thought 
worth  while  to  publish  the  results. 
The  salt  was  titrated  in  the  usual  way,  and  any  excess  of  silver 
nitrate  consumed  was  calculated  into  terms  of  chloride  of  potassium  by 
the  method  for  estimation  of  chlorides  in  presence  of  bromides  given 
in  "Muter's  Analytical  Chemistry,"  page  116.  Chloride  and  car- 
bonate are  generally  the  only  two  impurities  met  with,  and  of  these 
the  former  is  usually  present  in  larger  proportion  than  the  latter. 
Some  few  samples  did  contain  an  excessive  amount  of  carbonate, 
and  in  those  cases  the  results  obtained  by  the  above  method  would 
not  be  absolutely  correct ;  but  in  the  majority  of  cases,  where  the 
amount  of  carbonate  did  not  exceed  the  small  quantity  allowed  by 
the  U.S.P.,  the  results  would  hardly  be  affected. 
Where  a  larger  proportion  of  carbonate  exists,  very  accurate 
results  can  be  obtained  by  first  neutralizing  with  normal  hydro, 
bromic  acid  solution,  using  phenol  phthalein  as  indicator,  calculating 
the  carbonate  of  potassium  thus  found  into  bromide  of  potassium  and 
deducting  this  amount  from  the  total  bromide  of  potassium,  as  esti- 
mated subsequently  with  silver  nitrate  test  solution. 
It  will  be  seen,  by  an  examination  of  the  table,  that  very  reliable 
bromide  is  supplied  by  five  out  of  the  six  manufacturers  here  repre- 
sented. 
Two  samples  from  A  and  one  sample  from  B  were  rejected  as 
failing  to  answer  the  U.S.P.  tests.  From  C,  however,  we  find  a  large 
proportion  of  the  samples  had  to  be  rejected. 
