422 
Sodio-Bismuth  Tartrate  and  Pepsin. 
f  Am.  Jour,  Pharm. 
I       Sept.,  1885. 
of  the  normal  citrate  in  3  fluidgrams  is  mixed  with  a  strong  solution 
of  pepsin,  a  dense  gelatinous  magma  is  formed,  which  readily  dissolves 
on  dilution.  This  soluble  compound  appears  to  be  present  in  all  alka- 
line, neutral  or  but  slightly  acid  solutions  prepared  with  the  ammonio- 
citrate.  Unless  very  alkaline,  all  of  these  solutions  will  eventually 
deposit  most  of  the  normal  citrate  in  crystalline  crusts.  Alkaline 
solutions  are  also  apt  to  deposit  some  of  the  bismuth  as  metal  and  the 
remainder  as  citrate.  The  various  preparations  of  the  market  possess 
these  characters  in  different  degrees,  having  probably  all  a  similar  origin. 
A  permanent  acidulous  solution  has  long  been  a  desideratum. 
The  writer  found  ("American  Journal  Pharmacy,''  June,  1884) 
that  bismuth  citrate  unites  chemically  with  borax,  forming  a  perma- 
nent solution  having  a  decided  acid  reaction.  But  an  admixture  of 
pepsin  solution  causes  a  perceptible  flocculent  precipitate,  possibly  con- 
taining pepsin. 
On  treating  one  m.  of  dipotassio-bismuth  citrate  with  one  m.  of  boric 
acid  an  alkaline  solution  results.  With  two  ms.  of  boric  acid  an  acid- 
ulous product  is  obtained.  Neither  of  these  two  compounds  appears 
to  disturb  pepsin  solutions,  but  both  are  objectionable  from  lack  of 
sufficient  acidity  when  united  with  pepsin  in  solutions  more  than  ordi- 
narily concentrated. 
The  writer  found  ("American  Journal  Pharmacy,"  July,  1884)  that 
a  certain  proportion  of  monopotassio-bismuth  citrate  mixed  in  solution 
with  the  dipotassio  salt  imparted  an  acid  reaction.  The  mixture 
formed  permanent  solutions  with  pepsin,  and  the  writer  gave  a  for- 
mula for  such  a  preparation.  This  produced  necessarily  a  weak  form, 
and  trial  showed  that  a  much  more  concentrated  result  with  the  desired 
acidity  could  not  be  obtained. 
Owing  to  the  intractable  nature  of  the  bismuth  citrate  in  this  con- 
nection the  writer  concluded  to  avoid  its  use,  and  find  a  more  suitable 
bismuth  salt  to  take  its  place. 
The  next  experiments  were  made  with  tartaric  acid.  The  writer 
could  find  nothing  in  text-books  relating  to  the  existence,  the  compo- 
sition and  preparation  of  a  tartrate  of  bismuth.  Bismuth  oxynitrate 
or  bismuthyl  nitrate  when  heated  with  tartaric  acid  does  not  suffer 
decomposition,  and  hence  no  tartrate  is  formed  under  these  conditions. 
When  aided  by  some  nitric  acid  a  corresponding  proportion  of  tartrate 
forms.  When,  however,  enough  nitric  acid  is  added,  so  as  to  render 
the  whole  of  the  basic  salt  available,  a  perfect  solution  results.  On 
