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AmMJarUr;8P76rim' }  Bismuth  and  It  on.  i  o  5 
the  mixture  forms  a  clear  solution  with  ammonia  water,  the  crystalline 
mass  is  then  diluted  with  8  to  10  times  its  volume  of  water,  set  away 
for  a  short  time  to  let  the  citrate  subside,  and  the  clear  liquid  then  de- 
canted. The  crystalline  sediment  is  now  washed  3  or  4  times  in  a 
similar  manner,  drained  from  superfluous  water,  and  either  dried  on  a 
water-bath  or  by  exposure  in  the  open  air.  The  yield  is  about  13  2-3 
parts,  showing  that  the  salt  is  anhydrous,  and  therefore  its  formula  is 
Bi"'C,H„07. 
The  bismuthous  citrate,  as  such,  is  not  much  prescribed,  but  it  is  un- 
doubtedly superior  to  either  the  oxynitrate  or  oxycarbonate,  both  of 
which  are  medicinally  much  employed.  The  ammonio-citrate  is  con- 
siderably used,  and  as  no  method  thus  far  proposed  for  this  salt  has 
been  particularly  applicable,  the  writer's  new  process  for  preparing  the 
citrate  in  a  perfectly  pure  and  definite  state  will  make  it  possible  of 
producing  an  ammonio-citrate  with  great  ease  and  dispatch,  and  also  of 
perfect  purity. 
Dry  bismuthous  citrate,  treated  with  the  ordinary  ammonia  water,  dis 
solves  to  a  syrupy  liquid,  but  a  part  agglutinates  to  a  hard  white  mass 
unaffected  by  excess  of  ammonia  ;  if  gentle  heat  is  applied  this  dissolves 
and  on  cooling,  the  whole  forms  a  crystalline  mass,  soluble  in  water 
These  crystals,  dried  over  a  water-bath,  are  again  soluble  in  water 
The  yield  from  8  parts  of  the  citrate  is  nearly  10  parts.  This  product 
shows  that  there  are  several  modifications  of  the  ammonio-citrate, 
which  may  differ  in  chemical  constitution  as  well  as  in  physical  proper- 
ties. 
The  chemical  composition  of  the  ammonio-citrate  has  not  been  cor- 
rectly given.  The  writer  found  that  the  same  quantity  of  ammonia 
was  required  to  form  a  neutral  ammonio-citrate,  as  was  separately  re- 
quired to  form  normal  triammonium  citrate,  with  the  equivalent  of 
citric  acid  in  combination  as  bismuth  salt,  and  the  decomposition  may 
be  written  thus:  BiC6H507+3(NH4OH)=(NH4)3C6H507Bi(OH)3. 
The  compound  represented  by  the  second  number  is  assumed  to  be  a 
combination  of  normal  triammonium  citrate  with  normal  bismuthous 
hydrate,  and  this  compound  must  therefore  be  looked  upon  as  the  true 
ammonio-bismuthous  citrate,  as  all  other  formulae  are  based  upon  an 
analysis  of  the  scaled  salt,  which  must  of  necessity  be  an  indefinite  sub- 
stance. 
The  writer  has  also  found  that  normal  ferric  citrate  when  treated 
with  ammonia,  absorbs  an  amount  corresponding  as  normal  triammo- 
