118 
Bismuth  Oxyiodide. 
/Am.  Jour.  Pharni. 
1      March,  1887. 
Both  methods  advocate  the  use  of  considerable  mineral  acid  ;  that 
of  Mr.  C.  Mayo,  hydrochloric,  and  that  of  Mr.  Jos.  W.  England,  ni- 
tric acid.  Both  products  are  mixtures  of  bismuth  oxyiodide — with 
oxychloride  in  the  former,  and  oxynitrate  in  the  latter  case. 
It  occurred  to  me,  on  reading  the  papers  above  referred  to,  that  a 
pure  oxyiodide  might  be  made  by  boiling  together  oxynitrate  of  bis- 
muth and  potassium  iodide,  according  to  the  reaction: 
BiON03+KI=BiOI-j-Ki\03 
288     165-6  352-6  101 
The  two  salts,  dried  at  120°  C,  were  taken  in  molecular  ratio 
— 10  gm.  of  the  former,  5'75  gm.  of  the  latter — and  boiled  with  50 
cc.  water  for  half  an  hour.  The  color  of  the  oxynitrate  at  once 
changed  to  a  yellow,  and  rapidly  passed  into  a  brick-red.  It  is  not 
necessary  to  boil  the  mixture  in  order  to  get  the  brick-red  precipitate, 
since  the  reaction  also  takes  place  in  the  cold,  although  much  slower, 
requiring  several  hours  for  its  completion.  The  precipitate  was 
transferred  to  a  weighed  filter  and  washed  with  boiling  water  until 
the  washings  ceased  to  produce  turbidity  with  silver  nitrate.  It  was 
then  dried  at  120°  C,  and  weighed.  The  weight  was  11*490  gm. — 
deficient,  as  the  theoretical  yield  is  12*243  gm. 
The  filtrate,  proven  to  be  free  from  Bi,  contained  a  large  quantity 
of  potassium  iodide,  which  on  estimation  by  precipitation  with  silver 
nitrate  and  weighing  as  Agl,  proved  to  be  33  per  cent,  of  the  amount 
of  potassium  iodide  taken,  indicating  that  only  two-thirds  of  it  enter- 
ed into  the  reaction.  The  product  contained  oxynitrate,  the  detection 
of  which  in  the  presence  of  an  iodide  is  rather  difficult,  and  is  best 
determined  by  reducing  the  nitric  acid  to  ammonia  by  generating  H 
from  Zn  and  H2S04  and  liberating  NH3  by  adding  KOH.  The  purity 
of  the  compound  was  established  by  igniting  2  gm.  until  the  oxide, 
Bi2Os,  which  results  on  ignition  in  air,  ceases  to  lose  weight.  This 
cannot  be  accomplished  by  heating  with  a  Bunsen  burner,  as  some  oi 
the  iodine  is  still  retained  after  several  hours'  heating.  By  the  use 
of  a  blast-lamp,  after  heating  with  a  Bunsen  burner,  additional  vapors 
of  iodine  are  evolved,  and  the  residue,  only  after  complete  fusion, 
ceases  to  lose  weight.  The  amount  of  Bi2Os  was  1  *4l4  gm.,  or  70*70 
per  cent. 
The  Bi2Os  yielded  by  BiOI  is  equal  to  66  36  per  cent. ;  therefore, 
the  compound  is  not  pure  BiOI  as  previously  indicated  by  the  detec- 
