2 
PREPARATION  OF  LIQUOR  BISMUTH!. 
but  sparingly  soluble  in  citrate  of  ammonia,  even  at  the  boiling 
temperature.  The  presence  of  a  portion  of  nitrate  of  ammonia, 
through  insufficient  washing  of  the  teroxide,  will  effect  a  solu- 
tion. 
Secondly.  A  neutral  solution  of  citrate  of  bismuth,  obtained 
by  means  of  citrate  of  ammonia  and  ammonia,  or  by  ammonia 
alone,  of  such  strength  that  a  fluid  drachm  contains  one  grain  of 
teroxide  of  bismuth,  is  prone  to  decomposition.  This  change  is 
not  attended  by  the  deposition  of  a  basic  salt,  but  by  the  forma- 
tion of  humus  :  the  liquid  acquiring,  meanwhile,  a  disagreeable 
smell  and  taste,  which  totally  unfit  it  for  use. 
This  is  prevented  by  the  addition  of  alcohol,  whereby  it  is 
preserved  indefinitely.  A  concentrated  solution  appears  to  keep 
well  without  this  addition  of  spirit. 
Thirdly.  Mr.  Blunt's  assertion  that,  by  Mr.  Bartlett's  process, 
a  large  loss  of  citrate  of  bismuth  is  incurred,  is  erroneous,  and 
must  have  arisen  from  the  employment  of  nitric  acid,  sp.  gr.  1*5, 
(Ph.  Br.)  instead  of  that  of  the  sp.  gr.  1-42,  (U.  S.  Ph.)  Another 
inaccuracy  occurs  in  the  direction,  to  "  add  solution  of  potassa 
until  the  mixture  is  only  faintly  acid ;"  before  this  point  of  satu- 
ration is  reached,  the  precipitate,  first  formed,  will  be  entirely 
redissolved,  When  only  sufficient  potassa  is  added  to  neutralize 
the  nitric  acid,  the  citrate  of  bismuth  is  precipitated  ;  an  excess 
of  the  alkali  over  this  quantity  dissolves  the  citrate  of  bismuth, 
the  solution  still  having  an  acid  reaction.  Even  when  the  potassa 
is  employed  in  atomic  proportions  the  yield  of  citrate  of  bismuth 
is  no  larger  than  is  obtained  by  precipitation  with  citrate  of  po- 
tassa. The  process  recently  suggested  by  Mr.  Tichborne  (before 
alluded  to)  I  consider  highly  objectionable,  because  of  the  pres- 
ence of  nitrate  of  ammonia.  A  little  more  than  one  grain  of 
the  latter  salt  being  administered  with  every  grain  of  teroxide 
of  bismuth  :  such  an  addition  could  scarcely  fail  to  interfere  in- 
juriously with  the  therepeutical  action  of  the  bismuth.  Though 
I  have  employed  Mr.  Bartlett's  process  many  times,  and  with 
uniform  success,  I  prefer  a  modification  of  it,  embodying  the 
idea  of  Mr.  Blunt,  i.  e.,  in  dissolving  the  citric  acid  in  the  so- 
lution of  nitrate  of  bismuth,  and  adding  a  sufficient  quantity  of 
potassa  to  exactly  saturate  the  nitric  acid  employed.    The  ad- 
