Am.  Jour.  Pharm.  1 
Dec.  1, 1871.  j 
On  Citric  Acid,  Etc, 
539 
ANALYSIS  OF  CITRATE  OF  BISMUTH. 
This  citrate  of  bismuth  is  the  salt  obtained  by  precipitating  acid 
nitrate  of  bismuth  by  an  alkaline  neutral  citrate.    It  is  insoluble  in 
water,  and  may  be  obtained  pure  without  difficulty  ;  two  grammes  of 
this  salt  were  taken  and  decomposed  by  an  excess  of  caustic  potassa, 
at  a  moderate  heat.    The  precipitate  of  teroxide  of  bismuth  well 
washed  and  dried  was  found  to  weigh  1*122  grms.    The  washings 
were  collectel  together,  saturated  with  acetic  acid,  treated  by  acetate 
baryta  and  alcohol,  as  already  mentioned,  and  the  citrate  of  baryta 
thus  formed,  yielded  1*674  of  sulphate  of  baryta,  which  corresponds 
to  0*788  of  citric  acid.    The  balance  0*09  represents  the  equivalents 
of  water  and  the  loss.    Hence,  we  may  figure  the  result  thus  : 
Teroxide  of  Bismuth        1*122^  {  1*170  =  one  equivalent 
Citric  Acid  (anhydrous)   0*788  I       .    I  0*825-=  one 
Water       .       .       .     0*086  [  !  0-090  =  two 
T  r^  r^-^A  r  othcr  < 
Loss  .       .       .     0*004  f  ^^^^3^ 
2,085 
2,000  J 
From  this  we  may  deduct  for  Citrate  of  Bismuth  the  following 
formula  : — 
Bi03,Ci2H50,,+2HO--417. 
ANALYSIS  OF  THE  DOUBLE  CITRATE  OP  BISMUTH  AND  AMMONIA. 
This  salt  is  commonly  called  Ammonio-Citrate  of  Bismuth  or  solu- 
ble citrate  of  bismuth.  It  is  obtained  in  two  forms,  in  solution  and 
in  scales.  In  solution  it  may  be  either  acid  or  neutral,  in  scales  it  is 
always  acid  on  account  of  the  loss  of  some  ammonia  during  evapora- 
tion. It  is  very  extensively  used  in  medicine,  but  unfortunately  is 
rather  unstable  in  solution. 
The  analysis  of  the  neutral  salt  offered  no  difficulty :  2*085  grms. 
of  insoluble  citrate  bismuth  were  weighed  in  a  small  porcelain  dish,  a 
little  warm  water  added,  and  a  small  piece  of  litmus  paper  allowed 
to  float  on  it.  Then  a  filtered  solution  of  ammonia  containing  0*26 
of  ammonia  to  the  100  measures  was  cautiously  added,  the  mixture 
being  stirred  all  the  time.  As  the  last  drop  of  the  100  measures  fell 
into  the  porcelain  dish,  the  litmus  paper,  red  until  then,  turned  blue, 
and  in  the  same  time  the  liquid  became  perfectly  clear. 
This  gives  for  the  neutral  citrate  of  bismuth  and  ammonia  the  fol- 
lowing formula  : 
2  N  113,  BiOg,  Ci^H.Oii+^iHO. 
