ON  LIQUOR  FERRI  XODIDL 
173 
seen  a  liquor  of  Syrupus  Ferri  lodidi  which  did  not  turn  brown 
when  the  bottle  containing  it  was  frequently  opened  or  left  open. 
The  following  experiments  were  made  as  continuing  those  of 
Mr.  Maisch,  published  in  the  American  Journal  of  Pharmacy  of 
1854.  I  merely  give  the  results  of  the  different  tests,  the  de- 
tails being  too  lengthy.  The  solutions  were  all  made  with 
chemically  pure  iodine  and  fine  iron  wire. 
The  officinal  Liquor  Ferri  lodidi  contains  free  Jiydriodic 
acid,  and  the  quantity  of  iron  in  solution  is  not  sufficient  to  bind 
all  iodine. 
Cane  sugar  is  completely  changed  to  grape  sugar  by  heating 
with  dilute  hydriodic  acid.  Freshly  prepared  simple  syrup, 
diluted  with  water  and  heated  with  a  small  quantity  of  hy- 
driodic acid,  a  portion  of  the  liquid  precipitated  by  nitrate  of  sil- 
ver and  filtered,  the  excess  of  silver  removed  by  carbonate  of 
potassa,  and  the  filtered  liquid  added  to  a  hot  alkaline  solution 
of  potassio-tartrate  of  copper, — showed  the  distinct  reaction  of 
grape  sugar,  that  is,  precipitation  of  suboxide  of  copper.  To 
judge  from  the  test  with  ferri  cyanide  of  potassium,  as  lately 
given  by  Anthon,  no  cane  sugar  was  left  in  the  liquid. 
Cane  sugar  is  changed  to  glucose  with  hydriodic  acid,  and 
the  light  and  heat  of  the  sun  acting  together.  The  qualitative 
tests  were  made  as  above,  and  showed  the  presence  of  grape 
sugar,  but  only  in  a  small  proportion. 
•  Hydriodic  acid  dissolves  a  large  amount  of  hydrated  sesqui- 
oxide  of  iron,  forming  a  yellow  solution,  and  a  deep  blue  pre- 
cipitate with  ferro  cyanuret  of  potassium.  On  heating,  it  turns 
pale  under  escape  of  iodine,  and  then  precipitates  a  paler  blue. 
When  cane  sugar  is  present,  it  is  converted  into  glucose. 
The  browned  Liquor  Ferri  lodidi  heated  with  hydriodic 
acid  or  iodine  is  brought  bach  to  its  original  color  with  disengage- 
ment of  iodine  and  formation  of  grape  sugar.  It  then  gives  a  pale 
blue  precipitate  with  ferro  cyanuret  of  potassium,  which  turns  dark 
rapidly.  To  find  the  presence  of  any  acid  besides  hydriodic, 
I  precipitated  part  of  the  bleached  liquid  with  nitrate  of  silver, 
washed  the  precipitate,  and  decomposed  it  by  digestion  with 
metallic  zinc.  The  solution  of  zinc,  which  should  contain  all 
the  iodine  previously  combined  with  the  silver,  was  precipitated 
by  carbonate  of  soda,  and  the  alkaline  solution  tested  for  iodic 
