68 
Bismuth  Salicylate,  Basic. 
( Am.  Jour.  Pharm. 
I    February.  1900. 
No. 
Microscopical 
Appearance. 
Phj'sical 
Appearance. 
Per  Cent, 
of 
Bi203. 
Reaction. 
Moisture, 
Per  Cent, 
of. 
Nitrates. 
i   .  .  . 
f  Crystalline  and 
(  amorphous. 
White  and  \ 
bulky.  j 
63-51 
Acid. 
o"37 
Trace. 
2    .    .  . 
f  Crystalline  and 
(  amorphous. 
Bulky,  with  i 
pinkish  tint.  / 
64*15 
0-15 
3   •  •  ■ 
f  Crystalline  and 
\  amorphous. 
Pinkish  tint,  j 
66*20 
o-6o 
Much. 
4  •  • 
f  Crystalline  and 
\  amorphous. 
White  and  1 
bulky.  f 
64-36 
065 
5  •  •  • 
f  Crystalline  and 
\  amorphous. 
White  and  | 
bulky.  j 
64-50 
o*53 
Trace. 
6  .  .  . 
J  Crystalline  and 
\  amorphous. 
White  and  ) 
bulky.  J 
63-42 
0"20 
7  •  •  ■ 
|  Crystalline  and 
(  amorphous. 
White  and  \ 
bulky.  j 
61  "6o 
0-76 
All  contained  a  trace  of  chlorides. 
The  bismuth  oxide  was  estimated  in  the  usual  manner. 
Neither  the  metallic  copper  test  of  the  British  Pharmacopoeia, 
'98,  nor  the  test  recommended  by  the  German  Pharmacopoeia,  III, 
for  detecting  nitrates,  have  given  the  writer  satisfactory  results.  In 
fact,  small  quantities  of  added  nitrates  could  not  be  detected  by 
these  methods.  The  best  method  found  for  this  purpose,  thus  far, 
is  the  indigo  test,  which  is  applied  as  follows:  mix  0-5  gramme  of 
the  salicylate  with  3  c.c.  of  concentrated  sulphuric  acid  ;  a  reddish 
coloration  will  result,  the  intensity  depending  on  the  amount  of 
nitrate  present ;  to  this  solution  add  4  drops  of  indigo,  T.S.,  and 
if  much  nitrate  is  present  the  bluish  color  will  gradually  disappear 
at  the  ordinary  temperature.  A  small  amount  of  nitrate  will  rapidly 
destroy  the  color  on  warming. 
L.  Wolff1  distinguishes  the  subsalicylate  from  the  subnitrate  by 
means  of  the  microscope  ;  the  former  being  amorphous  or  granular 
while  the  latter  is  crystalline.  This  is  neither  a  satisfactory  test  for 
the  one  nor  the  other,  because  the  subnitrate  may  be  amorphous  and 
the  subsalicylate  is,  for  the  greater  part,  crystalline. 
Chlorides  and  sulphates  may  be  detected  by  igniting  I  gramme 
of  bismuth  subsalicylate  in  a  porcelain  crucible,  taking  up  the 
residue  in  pure  nitric  acid,  diluting  to  20  c.c.  with  water,  carefully 
avoiding  turbidity,  neither  barium  chloride  nor  silver  nitrate  should 
produce  more  than  a  faint  opalescence. 
1  1883,  Am.  Jour.  Pharm.,  55,  554. 
