354 
Bismuth  and  Pepsin. 
Am.  Jour.  Pharm. 
June,  1884. 
more  insoluble.  When  the  citrate  is  so  far  augmented  as  to  stand  in 
the  proportion  of  one  m.  to  one  m.  of  the  bicarbonate  the  whole  of  it 
does  not  combine.  By  treating  one  m.  of  bismuth  citrate  in  a  similar 
manner  with  two  ms.  of  sodium  bicarbonate  a  perfect  solution  is 
obtained  which  on  evaporation  yields  a  slightly  deliquescent  colorless 
scaled  salt.  The  same  results  when  one  m.  of  sodium  monocarbonate 
is  used.  An  excess  of  either  carbonate  on  the  application  of  heat  pre- 
cipitates a  bulky  and  gelatinous  bismuthyl  carbonate.  Excess  of  citrate 
is  absorbed  as  in  the  case  of  the  ammonium  salt.  A  small  excess  yields 
a  clear  solution  which  on  condensation  gives  a  white  granular  and 
soluble  residue.  An  increased  amount  of  citrate  up  to  one  m.  for  one 
m.  of  the  bicarbonate  enters  into  combination,  but  the  resulting  com- 
pound is  only  soluble  in  a  very  large  volume  of  water  aided  by  heat. 
One  m.  of  bismuth  citrate  treated  with  two  ms.  of  potassium  bicar- 
bonate or  one  m.  of  the  monocarbonate  in  the  preceding  manner  also 
gives  a  clear  solution,  decomposable  by  excess  of  carbonates,  and  yields 
on  evaporation  a  very  deliquescent  colorless  scaled  salt.  A  slight 
excess  of  citrate  readily  dissolves  and  then  produces,  as  in  case  of  the 
sodium  compound,  a  granular  very  soluble  residue.  An  increase  of 
the  citrate  up  to  one  m.  for  one  m.  of  the  bicarbonate  readily  combines 
forming  a  rather  freely  soluble  compound  having  a  decided  acid  reac- 
tion and  being  possessed  of  absolute  permanence  in  any  volume  of 
water.  It  is  not  decomposed  by  neutral  chlorides,  but  chlorhydric  acid 
destroys  it  with  precipitation. 
The  salt  generated  by  two  ms.  of  potassium  bicarbonate  and  one  m. 
of  bismuth  citrate,  and  to  which  sodium  and  ammonium  form  cor- 
responding analogues,  is  constitutionally  represented  by  the  formula : 
Bi  =  (OH), 
I 
Ci  =  K2 
Then  the  salt  formed  by  one  m.  of  the  bicarbonate  may  be  indicated 
by  the  formula : 
Bi  —  (OH) 
II 
Ci  — K 
There  are,  however,  plausible  reasons  that  the  structural  symbol  is 
Bi  =  0 
