^"p^n  fg™  }   Reaction  between  Iodide  Potassium^  &c.  85 
as  this  article  is  usually  charged  from  5s.  to  6s.  per  ft),  you  will  see 
how  large  a  price  we  sometimes  pay  for  our  credulity.  We  ought  not 
to  allow  ourselves  to  be  imposed  upon  in  this  manner.  The  process 
of  the  Pharmacopoeia  is  neither  expensive  nor  difficult,  and  I  strongly 
advocate  making  this  and  other  preparations  for  ourselves,  or,  when 
this  is  not  practicable,  to  subject  them  to  strict  examination  before 
taking  into  stock.  I  have  great  suspicions  of  many  of  these  concen- 
trated preparations,  and  doubt  not  that,  could  they  all  be  examined 
with  the  same  facility  as  this  one,  many  would  be  found  very  deficient. 
— PJiarm.  Journ.^  Lond.,  December,  10th,  1870. 
THE   REACTION    BETWEEN   IODIDE  OF  POTASSIUM  AND 
SUB-NITRATE  OF  BISMUTH. 
By  W.  Bathurst  Woodman,  M.  D.,  and  C.  Meymott  Tidy,  M.  B. 
An  out-patient  attending  at  the  London  Hospital  was  taking  the 
bismuth  mixture  of  its  Pharmacopoeia,  when  it  was  thought  advisable 
to  add  iodide  of  potassium  to  the  previous  prescription.  When  she 
came  the  following  time,  she  appeared  much  alarmed  at  a  red  pre- 
cipitate in  the  mixture,  which  she  supposed  to  be  "  red  lead"  purposely 
put  in  by  some  neighbor,  the  sediment  having  been  almost  colorless 
when  she  reached  home.  As  no  mention  is  made  in  the  ordinary 
text-books  of  Materia  Medica  of  the  decomposition  which  takes  place, 
although  it  is  doubtless  well  known  to  metallurgists,  it  occurred  to 
the  authors  to  examine  the  reaction  a  little  more  closely.  The  change 
takes,  place  slowly,  and  appears  to  consist  in  the  formation  of  an 
iodide  of  bismuth,  potassic  nitrate  remaining  in  solution.  This  iodide 
of  bismuth  is  a  dark  red  substance  of  cubic  form,  and  seems  to  be  a 
simple  iodide,  which  is  almost  insoluble  both  in  water  and  in  excess 
of  potassic  iodide.  Some  of  its  properties  are  curious.  It  is  a  very 
insoluble  substance  ;  for,  in  addition  to  what  is  mentioned  above,  we 
may  add  that  saturated  solutions  of  chloride  of  ammonium,  chloride 
of  sodium,  ferrocyanide  of  potassium,  and  corrosive  sublimate,  do  not 
dissolve  it  in  any  appreciable  proportions.  Acetic  acid  dissolves  it 
slightly,  without  elfervesence.  On  boiling  with  liquor  potassse  or 
ammonia,  the  hydrated  oxide  of  bismuth  (H  Bi  0^)  is  produced,  which 
is  insoluble  in  excess  of  either  reagent.  On  treating  this  iodide  with 
strong  nitric  acid,  there  was  active  efi'ervescence  ;  fumes  of  iodide  being 
