10 
Bismuth  Subiodide. 
Am.  Jour.  Pharm, 
Jan.,  1887. 
It  is  a  matter  of  interest,  that  the  first  general  statement  concerning 
this  oxysalt  was,  probably,  made  by  Messrs  Woodman  and  Tidy/  who 
found  it  in  an  old  mixture  of  potassium  iodide  and  bismuth  subnitrate 
given,  by  them,  to  one  of  the  patients,  of  the  London  Hospital.  They 
stated  that  the  change  took  place  slowly,  with  the  formation  of  the 
soluble  potassium  nitrate  and  the  insoluble  bismuth  iodide.  This 
iodide,  they  isolated,  was  a  fine,  brick-red  powder,  consisting  of  very 
small,  cubical  crystals,  almost  insoluble,  both  in  water  and  solution  of 
potassium  iodide.  Saturated  solutions  of  chloride  of  ammonium, 
chloride  of  sodium,  ferrocyanide  of  potassium  and  corrosive  sublimate, 
failed  to  dissolve  it  in  any  appreciable  quantity.  Acetic  acid  dissolved 
it,  slightly,  without  effervescence.  On  boiling  it  with  a  solution  of 
potassium  or  ammonium  hydrate,  the  hydrated  oxide  of  bismuth  was 
produced,  which  was  insoluble  in  excess  of  either  reagent.  On  treat- 
ing the  iodide  with  strong  nitric  acid,  there  was  strong  effervescence, 
fumes  of  iodine  being  given  off,  with  a  residue  entirely  soluble  in 
alcohol  and  which,  upon  further  examination,  proved  to  be  pure  iodine. 
Acid  solution  of  bismuth  nitrate  remained,  which  was  not  precipitated 
by  a  small  quantity  of  water  or  until  neutralized.  With  hydro- 
chloric or  sulphuric  acid,  there  was  no  effervescence,  but  iodine  was 
again  precipitated,  and,  with  the  sulphuric  acid,  some  iodic  acid  was 
formed.  Oxalic  acid  also  decomposed  the  salt,  setting  free  the  iodine  ; 
the  action  being  somewhat  slower  than  it  was  in  the  case  of  the  min- 
eral acids.  A  few  trials  of  it,  internally,  in  doses  of  from  5  to  20 
grains,  appeared  to  indicate  that  it  was.  not  an  energetic  therapeutic 
agent  •  which  apparent  lack  of  activity  was  ascribed  to  its  compara- 
tive insolubility. 
As  previously  stated,  the  high  cost  of  this  bismuth  dressing  ($12  a 
pound),  has  effectually  prohibited  its  general  employment  and  the  wri- 
ter was  led  to  make  a  series  of  experiments,  in  the  Philadelphia  Hos- 
pital, concerning  its  mode  of  preparation,  in  order  to  ascertain  whether 
some  method  could  not  be  devised,  whereby  the  compound  could  be 
much  more  readily  and  cheaply  made. 
The  general  method,  as  stated  to  be  at  present  employed,  i.  e.,  solu- 
tion of  bismuth  subnitrate  in  sufficient  strong  nitric  or  hydrochloric 
acid,  and  precipitation  in,  or  with,  potassium  iodide  solution,  is  very 
unsatisfactory  in  practice,  in  that  the  precipitates  formed,  are  of  very 
1  British  Med.  Jour.,  vide  Amer.  Jour.  Pharm.,  Feb.,  1871.  p.  85. 
