AmiugYstPih887m'}    Some  Official  and  Non-Official  Iodides.  391 
convert  the  nitric  acid  into  calcium  nitrate.  The  first  addition  of  the 
carbonate  causes  a  yellow  precipitate,  which  becomes  more  and  more  red 
with  successive  additions  of  the  carbonate.  When  finally  all  the 
nitric  acid  is  neutralized  the  brick-red  compound  permanently  remains. 
Based  upon  these  conditions,  the  following  process  is  suggested : 
Bismuth-oxyl  nitrate   288  grains. 
Potassium  iodide   166  <{ 
Calcium  carbonate   200  lt 
Nitric  acid..,   360  " 
Acetic  acid  ,   2  fluid-ounces. 
Water  sufficient. 
Mix  the  nitric  acid  with  two  fluid-drams  of  water,  and  gradually 
add  the  bismuth-oxyl  nitrate.  To  the  crystalline  mass  which  has  re- 
sulted, add  the  acetic  acid,  and  stir  the  mixture  until  perfect  solution 
has  resulted.  Dissolve  the  potassium  iodide  in  two  fluid-ounces  of 
water,  and  pour  the  solution  into  the  previous  one.  To  the  black 
mixture  add  gradually  the  calcium  carbonate.  When  the  reaction  is 
completed  incorporate  two  fluid-ounces  of  water  and  decant  the  super- 
natant liquor  after  the  red  precipitate  has  subsided ;  to  this  residue  add 
two  fluid-ounces  of  water,  pour  the  mixture  into  a  plain  filter,  and 
after  having  thoroughly  washed  the  powder  expose  it  in  the  air  until 
perfectly  dry. 
It  seems  not  inappropriate  here  to  remark  that  bismuth  pentoxide 
or  biemuthic  anhydrate  might  perhaps  possess  antiseptic  properties  of 
some  medicinal  value.  The  compound  is  easily  prepared  as  a  red- 
brown  powder  by  treating  bismuth-oxyl  nitrate  with  excess  of  solution 
jo  chlorinated  soda  and  washing  the  precipitate  with  dilute  nitric  acid. 
In  this  connection  the  writer  would  also  state  that  the  bismuth  when 
present  in  solution  in  very  small  proportion  is  readily  reduced  to  the 
metallic  state  by  a  large  excess  of  an  ammoniacal  solution  of  ferrous 
citrate.  The  reduction  takes  place  in  the  cold  but  is  facilitated  by 
heat. 
When  the  black  bismuth  iodide  is  mixed  with  solution  of  potassium 
citrate  a  purple-red  precipitate  remains  and  acidic  potassio-bismuth 
citrate  is  dissolved.  On  setting  the  liquor  aside  the  acidic  salt  sepa- 
rates in  seemingly  crystalline  crusts.  This  residue,  when  treated  with 
water,  again  dissolves,  but  meanwhile  gives  a  mixture  which  on  stirring 
exhibits  the  striking  pearly  streaks  already  mentioned  in  connection 
with  other  salts.  Under  the  microscope,  however,  no  crystals  are  vis- 
ible, but  an  abundant  amorphous  matter. 
