AmASustPiSm"}     Potassium  Bromide  with  Caffeine.  425 
contents  of  the  beaker  to  a  brisk  boil,  and  re-titrate  the  excess  of 
potassium  hydroxide.  From  the  results  thus  obtained,  the  per- 
cent, of  the  combined  nitric  acid  radical  can  readily  be  calculated. 
The  results  recorded  above  may  be  a  trifle  low,  since  it  is  well 
known  that  bismuth  subnitrate  is  with  difficulty  completely  decom- 
posed with  dilute  alkaline  solutions,  even  at  the  boiling  point. 
The  samples  were  taken  from  original  packages.  The  U.  S.  Phar- 
macopoeial  requirements  were  complied  with  in  every  respect,  ex- 
cept that  from  an  appreciable  quantity  to  a  minute  trace  of  chlorides 
was  present  in  every  case,  and  No.  5  was  contaminated  with  the 
carbonate. 
The  above  results  show  that  the  bismuth  subnitrate  manufactured 
in  Philadelphia,  New  York  and  Brooklyn,  although  not  a  theoretical 
chemical  compound,  is  not  so  excessively  "  basic  "  as  those  reported 
on  by  Dr.  Curtman,  excepting  No.  5. 
Philadelphia,  Pa.,  July,  1896. 
THE  VALUATION  OF  GRANULAR  EFFERVESCENT 
POTASSIUM  BROMIDE  WITH  CAFFEINE. 
By  Charts  E.  Alexander,  Ph.G. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of 
'     Pharmacy.    No.  155. 
In  order  to  estimate  the  medicinal  constituents  of  granular  effer- 
vescent potassium  bromide  with  caffeine,  the  writer  has  devised  and 
used  the  following  methods  with  gratifying  results  : 
One  gramme  of  the  preparation  is  dissolved  in  about  30  c.c.  of 
water,  the  solution  acidified  with  nitric  acid,  warmed,  and,  while  con- 
stantly stirred,  completely  precipitated  with  silver  nitrate  test  solu- 
tion. The  precipitate  of  silver  bromide  may  be  mixed  with  silver 
chloride  from  soluble  chlorides  in  the  original  preparation.  It  is, 
therefore,  collected  on  balanced  filters,  washed  thoroughly  with  hot 
water,  and  afterwards  treated  on  the  filter  with  a  10  per  cent,  solu- 
tion of  ammonium  carbonate,  applied  in  small  quantities  and  uni- 
formly distributed,  to  dissolve  silver  chloride.  The  precipitate  is 
then  washed  free  of  ammonium  carbonate  with  cold  water,  and 
dried  to  constant  weight  at  a  temperature  not  exceeding  1300  C. 
The  amount  of  potassium  bromide  is  then  calculated  by  proportion 
horn  the  weight  of  silver  bromide  found. 
