Am.  Jour.  Pharm.  \ 
April,  1886.  j 
Pismuthi  Citras,  Etc. 
Ill 
Take  of— 
Subnitrate  of  bismuth,  1  ounce  and  180  grains. 
Citric  acid,  1  ounce  and  60  grains. 
Nitric  acid,  1£  fluid  ounces. 
Solution  of  ammonia,  ) 
Distilled  water,  }  of  each  a  ^ffi^ency. 
Heat  the  subnitrate  of  bismuth  with  the  nitric  acid  until  the  salt  has 
dissolved  and  the  solution  has  acquired  the  appearance  of  a  syrup  ; 
with  this  mix  the  citric  acid  previously  dissolved  in  an  ounce  of  water 
by  the  aid  of  heat ;  divide  the  solution  into  two  equal  portions,  and 
to  one  portion  add  solution  of  ammonia  until  the  precipitate  at  first 
formed  is  redissolved ;  dilute  with  water  to  1  pint,  add  the  remaining 
portion  of  the  bismuth  solution  with  constant  stirring,  collect  the 
precipitate  on  a  calico  filter,  and  wash  with  water  until  the  vvashings 
are  free  from  acid.  Transfer  the  precipitate  to  a  suitable  vessel  and 
add  solution  of  ammonia  gradually  and  with  constant  stirring  until 
the  precipitate  is  just  dissolved.  Dilute  with  water  to  1  pint  (im- 
perial). 
A  competent  practical  pharmacist  has  at  my  request  tried  this  for- 
mula, and  he  remarks,  "It  is  an  absolute  contrast,  in  its  simplicity, 
to  the  B.  P.  method;"  but  he  fears  that  there  is  a  great  loss  of  bis- 
muth in  washing.  This  I  had  previously  determined  to  be  under 
3  per  cent.,  having  obtained  97  per  cent,  of  the  theoretical  yield  of 
citrate.  Hence,  in  the  formula  I  give  a  slight  excess  of  bismuth 
over  what  is  required  for  800  grains  of  citrate,  and  as  the  B.  P. 
citrate  may  contain  2  per  cent,  of  water,  the  loss  in  the  washings  is 
compensated  by  these  provisions.  Citric  acid  is  also  in  excess.  With 
the  theoretical  quantity  the  bismuth  is  apt  to  crystallize  out  before 
ammonia  can  be  added.  This  is  not  by  any  means  a  fatal  objection ; 
therefore  on  the  large  scale  it  will  be  possible  to  modify  the  propor- 
tions which  are  given.  Thus  for  citrate  of  bismuth  the  quantities 
might  be — bismuth  subnitrate,  13  parts;  nitric  acid,  14  fluid  parts; 
citric  acid,  10  parts. 
It  is  obvious  that  the  1867  process  may  be  modified  according  to 
the  principle  herein  involved,  and  this  may  perhaps  be  the  gentlest 
way  for  the  Pharmacopoeia  authorities  to  recant. 
Note, — Since  the  foregoing  was  written  I  have  observed  that  Mr. 
Proctor,  in  his  "  Lectures  on  Pharmacy,"  recommends  this  process. 
I  wonder  why  it  has  slipped  recognition  by  the  authorities  ? — Phar. 
Jour,  and  Trans.,  Jan.  16,  1886,  p.  602. 
12 
