PREPARATION  OF  LIQUOR  BISMUTHI. 
3 
vantage  being  that  the  citrate  of  bismuth  thereby  produced  is 
more  readily  washed,  and  is  more  rapidly  and  completely  dis- 
solved by  ammonia. 
The  process  is  as  follows  : 
Take  of  Subcarbonate  of  bismuth  a  troyounce ; 
Citric  acid  (in  powder)  420  grains ; 
Nitric  acid,  sp.  gr.  1-42,  a  troyounce  and  a  half; 
Pure  caustic  potassa  450  grains  ; 
Distilled  water, 
Alcohol,  each,  a  sufficient  quantity. 
Dissolve,  by  gradual  addition,  the  subcarbonate  of  bismuth  in 
the  nitric  acid,  and,  when  effervescence  has  ceased,  dilute  the  so- 
lution with  a  iluidounce  and  a  half  of  distill  3d  water  ;  now  add 
the  citric  acid,  and  stir  until  it  is  dissolved.  In  eight  fluidounces 
of  distilled  water  dissolve  the  caustic  potassa,  and  add  this  gradu- 
ally to  the  acid  solution.  Permit  the  mixture  to  stand  for  six  or 
eight  hours,  then  transfer  to  a  moistened  paper  filter,  and  wash 
the  precipitate  until  the  washings  no  longer  contain  nitrate  of 
potassa.  Transfer  the  still  moist  magma  to  a  dish,  and  add,  very 
gradually,  water  of  ammonia  until  the  precipitate  is  dissolved, 
and  a  neutral  solution  is  obtained.  Dilute  this  solution  with  an 
equal  volume  of  distilled  water,  and  treat  half  a  fluidounce  of 
the  liquid  with  hydrosulphate  of  ammonia,  in  slight  excess ;  wash 
the  precipitate  on  a  tarred  filter,  dry  on  a  water  bath  and  weigh. 
Multiply  the  weight  of  the  sulphide  of  bismuth  by  the  fraction 
•908,  to  determine  its  equivalent  in  teroxide  of  bismuth.  Apply 
the  same  ratio  to  the  remainder  of  the  liquid,  and  dilute  it  to 
such  an  extent  that  a  fluid  drachm  shall  contain  one  grain  of  ter- 
oxide of  bismuth,  seven-eighths  of  which  measure  must  be  made 
up  with  distilled  water,  and  the  remainder  with  alcohol.  The 
average  product  of  liquor  bismuthi,  from  a  troyounce  of  sub- 
carbonate of  bismuth,  was  50  fluidounces,  indicating  a  loss  of  bis- 
muth amounting  to  7*6  per  cent. 
This  loss  is  occasioned  by  the  slight  solubility  of  citrate  of 
bismuth  in  the  washings,  and  though  this  portion  may  be  recov- 
ered, it  is  too  small  in  amount  to  compensate  for  the  time  and 
trouble  necessarily  expended  in  its  separation. 
Chicago,  December,  1865. 
