2 
BISMUTHI  ET  AMMONIJE  CITRAS. 
tbod  suggested,  that  of  substituting  citrate  of  bismuth  for  the 
oxide,  yielded  a  more  satisfactory  product. 
The  writer,  having  observed  the  solution  of  citrate  of  bismuth, 
obtained  by  the  addition  of  ammonia,  to  have  an  acid  reaction, 
and  also  that  an  excess  of  that  alkali  occasioned  a  precipitate 
of  oxide  of  bismuth,  inferred  the  existence  of  a  compound  salt 
of  bismuth  and  ammonia ;  this  was  subsequently  confirmed. 
The  following  formulas,  suggested  by  theory  and  numerous 
experiments,  were  finally  adopted  ; 
Bismuth  i  Citras. 
Take  of 
Subcarbonate  of  Bismuth  a  troyounce ; 
Citrate  of  Potassa  a  troyounce  and  120  grains  ; 
Nitric  Acid  a  troyounce  and  a  half  ; 
Distilled  water  a  sufficient  quantity. 
Dissolve  the  subcarbonate  of  bismuth  in  the  nitric  acid,  and, 
when  effervescence  has  ceased,  dilute  the  solution  with  a  fluid- 
ounce  and  a  half  of  distilled  water,  gradually  added.  Dissolve 
the  citrate  of  potassa  in  two  pints  of  distilled  water,  and  to  this 
liquid  add  slowly,  with  constant  stirring,  the  acid  solution  of 
bismuth. 
Permit  the  mixture  to  stand  for  several  hours ;  then  pour  it 
on  a  moistened  paper  filter,  and,  when  the  liquid  has  nearly 
ceased  to  pass,  cover  the  surface  of  the  precipitate  with  distilled 
water. 
Repeat  this  operation  until  the  washings  no  longer  contain 
nitric  acid.  Allow  the  magma  to  drain,  and  dry  it  on  bibulous 
paper,  with  a  gentle  heat. 
Bismuthi  et  Ammonia?  Citras. 
Take  of 
Citrate  of  Bismuth,  in  powder,  a  convenient  quantity ; 
Stronger  Water  of  Ammonia, 
Distilled  Water,  each,  a  sufficient  quantity. 
.Rub  the  citrate  of  bismuth  with  sufficient  distilled  water  to  re- 
duce it  to  a  uniform  pasty  consistence,  and  add,  cautiously, 
with  constant  trituration,  stronger  water  of  ammonia,  until  a 
solution  is  obtained,  observing  to  avoid  an  excess  of  ammonia. 
