446 
Bismuth  Subnitrate. 
Am.  Jour.  Pharm. 
Sept .  1888. 
The  specimens  were  made  by  varying  the  acidity  of  the  mixed 
bismuth  nitrate  and  ammonia  solutions:  No.  1,  was  of  neutral  reac- 
tion ;  No.  2,  faintly  acid ;  No.  3,  the  preceding  while  still  moist  treated 
with  a  slight  though  decided  excess  of  nitric  acid ;  No.  4,  made  by 
pouring  the  bismuth  nitrate  solution  into  the  diluted  ammonia  and 
acidulating  with  HNO3;  No.  5,  contained  about  J  per  cent,  free 
HNO3;  No.  6,  contained  1  per  cent,  free  HNO3.  The  mixtures 
were  poured  into  small  percolators  and,  after  draining,  washed  with 
0*2  per  cent.  NH4NO3  solution.  In  the  first  four  samples  little  more 
than  the  quantity  equal  to  the  retained  solution  had  to  be  added  be- 
fore the  washings  gave  an  entirely  neutral  reaction ;  in  the  last  two, 
after  adding  more  than  twice  this  quantity  the  washings  were  decided- 
ly acid  and  the  ammonium  nitrate  was  present  in  no  larger  quantity 
than  corresponded  to  the  solution  used  in  washing,  showing  the  0*2 
per  cent,  solution  of  NH4NO3  removed  part  of  the  acid  from  the  pre- 
cipitates. The  washing  was  stopped  and  after  draining  the  precipitate, 
this  was  dried  as  much  as  possible  by  pressing  between  filter  paper, 
finally  at  a  temperature  below  70 °C. 
The  amount  of  ammonium  nitrate  remaining  in  the  dry  product  was 
inconsiderable. 
In  appearance  Nos.  4  and  6  were  the  handsomest  products,  being 
almost  a  pure  white ;  the  others  had  a  more  or  less  yellowish  tint 
dependent  on  amount  of  oxide  contained  in  them.  No.  6  on  heating 
to  drive  off  the  moisture  did  not  deepen  in  color,  while  No.  4  did, 
thus  betraying  the  amount  of  oxide  it  contained. 
Bi,0, 
H2O 
Bi  0X0  3 
BigO; 
No.  1  ... 
9-94 
2-47 
5301 
44-53 
a  0 
 86-55 
10-91 
2-50 
58-19 
39-27 
"  3,... 
,80-35 
16-35 
3-13 
87-20 
9.50 
"   4  ,., 
 80-20 
16-18 
3-43 
86-29 
10-09 
"   5  ... 
,,79-40 
17-28 
3-25 
92-16 
4-52 
"    6  ... 
 79  15 
18-10 
2-50 
96-53 
0-72 
These  results  show  that  even  in  the  presence  of  several  per  cent,  of 
ammonium  nitrate  ammonium  hydrate  readily  unites  with  the  acid  of 
the  freshly  precipitated  salt,  giving  a  very  basic  product;  that 
Bi  ONO3  can  only  be  obtained  from  decidedly  acid  solutions  ;  that 
the  product  must  be  very  sparingly  washed  (best  by  displacement  in 
a  percolator) ;  that  dilute  NH4  NO3  solution  containing  less  than  0.5 
per  cent,  will  remove  acid  from  Bi  ONO3  (result  of  experiments  with 
