394       CONVERSION  OF  CANE  SUGAR  INTO  GRAPE  SUGAR. 
changed,  it  not  presenting  any  distinct  crystalline  form,  but 
granular  in  appearance,  I  suspected  a  modification  of  the  sugar 
into  grape  sugar  had  taken  place;  and  with  the  view  of  ascertain- 
ing if  such  was  the  case,  I  removed  a  portion  of  the  mass  from 
the  bottle,  and  pressed  it  in  a  cloth  to  remove  as  much  as  possible 
the  fluid  portion.  The  mass  left  I  dissolved  in  water,  and  to  the 
solution  added  sesquicarbonate  of  ammonia  to  remove  the  iron. 
The  precipitate  was  removed  by  filtration,  to  the  filtrate  Donald- 
son's test  was  added,  and  the  whole  heated  to  ebullition.  A  pre- 
cipitate of  the  red  suboxide  of  copper  was  immediately  produced, 
indicating  the  presence  of  grape  sugar.  The  appearance  of  the 
mass,  and  the  above  reaction  of  the  test  applied,  was  so  conclu- 
sive to  me  of  the  presence  of  grape  sugar,  that  I  deemed  any 
farther  test  unnecessary.  This  change  of  ordinary  cane  sugar 
into  grape  sugar  in  the  syrup  of  iodide  of  iron  is  to  me  inexplicable. 
Professor  Procter,  to  whom  I  mentioned  the  fact,  suggests  the 
presence  of  free  hydriodic  acid  in  the  syrup,  as  the  cause  of  the 
alteration.  There  certainly  was  not  any  free  acid  in  the  original 
syrup ;  if  so,  why  not  the  whole  of  it  undergo  the  same  change  ? 
it  was  all  made  at  the  same  time  and  equally  protected  from 
the  air.  The  fluid  floating  upon  the  solid  mass  was  of  a  darker 
color  than  the  original  preparation ;  free  hydriodic  acid  might 
have  been  present  in  it;  I  did  not  examine  it  for  it. 
Since  I  have  observed  this  change  in  the  above  preparation, 
Dr.  Chapman,  of  this  city,  to  whom  I  mentioned  it,  stated  that  he 
had  observed  a  similar  phenomenon  to  occur  in  the  syrup  of  proto- 
nitrate  of  iron,  a  quantity  of  which  he  had  carefully  prepared  some 
time  since,  and  put  up  in  phials  holding  two  ounces  each.  Some 
of  the  bottles  of  syrup  commenced  to  deposit  a  granular  sub- 
stance ;  others  evinced  no  disposition  to  change. 
One  of  the  bottles  of  syrup  thus  changed  was  given  me  for 
examination,  which  I  tested  in  the  same  manner  as  the  syrup  of 
iodide  of  iron,  and  with  like  results.  The  presence  of  free  acid  in 
this  last  preparation  might,  in  fact,  be  the  cause  ;  but  the  singu- 
larity of  the  change  taking  place  in  a  portion  only  of  it,  as  in  the 
former,  I  think  requires  some  other  explanation. 
In  the  July  number  of  the  London  Pharmaceutical  Journal, 
I  find  mention  of  a  curious  fact  discovered  by  E.  Maumene,  which, 
perhaps,  explains  the  reaction  in  these  two  preparations.  He 
