424 
Bismuth  Subnitrate. 
( Am.  Jour.  Pharm. 
I     August,  1896. 
metallic  bismuth,  and  (2)  the  per  cent,  of  combined  nitric  acid. 
These  were  estimated  in  the  ten  samples  examined  above  with  the 
following  results : 
Number. 
Per  Cent,  of  Bis- 
muth Oxide. 
Per  Cent,  of 
Nitric  Acid 
Radical  (N03). 
Per  Cent,  of  BiONO 
H20.  Calculated 
from  N03. 
83-23 
1878 
92  09 
81-26 
18-38 
90-14 
81-46 
17-88 
8769 
4  
83-26 
18-44 
90*43 
82-50 
14-12 
69-25 
6  
81  -oo 
17-76 
87-10 
7  
8ri5 
1770 
86-8i 
8  
81-36 
1876 
92*00 
9  •  
8l -02 
19-21 
94*2i 
83-OI 
19-68 
96-51 
The  bismuth  oxide  was  determined  by  ignition  in  the  usual  way. 
Any  mixture  of  bismuth  subnitrate  and  bismuth  hydroxide  would 
not  vary  materially  in  the  percentage  of  bismuth  oxide  from  the 
above  results,  consequently  this  source  of  information  is  of  little 
value  as  regards  the  amount  of  bismuth  subnitrate. 
Several  methods  were  tried  for  estimating  the  combined  nitric 
acid.  The  necessary  apparatus  for  the  absolute  or  copper  oxide 
method  was  not  at  the  writer's  disposal.  Gunning's  method,  modi- 
fied for  nitrates,1  gave  unsatisfactory  results,  being  non-concordant 
and  low.  This  was  undoubtedly  due  to  a  loss  of  nitric  acid,  en- 
countered when  the  sulphuric-salicylic  acid  mixture  was  added  to 
the  bismuth  subnitrate.  The  odor  of  nitric  acid  was  pronounced  at 
the  mouth  of  the  digestion  flask.  The  method  employed  by  Dr.  Curt- 
man  did  not  yield  satisfactory  results  in  the  writer's  hands.  The 
end  reaction  was  difficult  to  determine,  on  account  of  the  reflection 
of  the  pinkish-colored  precipitate,  and  the  results  were  even  lower 
than  those  obtained  by  Gunning's  process.  The  volumetric  method 
giving  the  writer  the  most  satisfactory  results  is  as  follows :  Suspend 
any  given  weight  of  the  salt  in  about  10  equivalents  of  distilled 
water,  in  a  suitable  beaker;  add  an  excess  of  normal  potassium 
hydroxide  and  a  few  drops  of  phenolphthalein  solution ;  bring  the 
1 1895,  "  Methods  of  Analysis,  Association  of  Official  Agricultural  Chemists." 
p.  18. 
