i6o 
Caramelization  in  Riuas's  Test. 
Jour.  Pharm. 
pril,  1910. 
This  in  no  way  invalidates  the  explanation  by  resinification.  For 
it  is  probable  that  aldehyde-resin  is  a  product  resulting  from  the 
continued  condensation  of  aldol  molecules  with  the  elimination  of 
water,  just  as  aldol  itself  easily  loses  one  molecule  of  water  when 
heated,  with  the  formation  of  crotonaldehyde : 
In  closing,  it  seems  permissible  to  return  to  the  case  of  syrup 
of  ferrous  iodide.  Although  we  deal  here  at  first  with  a  neutral 
syrup,  it  is  possible  to  draw  an  explanation,  from  the  accepted  facts 
of  chemistry  without  recourse  to  the  assumption  of  caramelization. 
Ferrous  iodide  is  the  salt  of  a  weak  base  and  a  strong  acid  and 
therefore  undergoes  hydrolysis  with  the  formation  of  hydriodic 
acid  and  ferrous  hydroxide,  or  basic  salts  of  ferrous  iron, 
FeI2  +  2H20  =  2HI  +  Fe(OH)2,  or  basic  salts.  The  fact  that 
this  syrup  becomes  acid  as  it  ages  was  pointed  out  by  W.  F.  Horn 
in  the  paper  already  cited.20  The  cane-sugar  then  would  be  expected 
to  undergo,  at  least  in  part,  an  inversion,  or  hydrolysis,  such  as  it 
is  well  known  to  undergo  in  the  presence  of  strong  acids  such  as 
hydrochloric  acid.  As  to  strength,  hydriodic  acid  is  to  be  classed 
with  hydrochloric  acid,  and  it  would  catalyze  this  hydrolysis  in  much 
the  same  way  as  hydrochloric  acid.  This  inversion  would  likely 
produce  the  two  hexoses,  d-glucose  and  d-fructose,  well  known  to 
be  produced  in  the  presence  of  other  strong  acids : 
These  two  hexoses  may  then  undergo  the  change  which  is  known 
as  a  general  reaction  for  hexoses  in  the  presence  of  hydrochloric 
acid,  namely,  the  conversion  into  levulinic  acid,  CH3.CO.CH2.CH2.- 
COOH,  with  the  simultaneous  production  of  the  brown  substances 
known  to  be  produced  always  in  this  transformation  and  called 
"  Humus  Substances."  21  Other  reactions  may  occur  at  the  same 
time,22  and  the  browned  syrup  of  ferrous  iodide  offers  an  open 
field  for  extensive  investigation. 
H20  =  CH3.CH:CH.Q 
C12H22On  -\-  H20  —  C6H12Oe  -f-  C6H12Oe 
20  Proceedings  Penna.  Pharm.  Assoc.,  1903,  p.  112. 
Holleman- Walker,  p.  269. 
2~Cf.  W.  F.  Horn,  loc.  cit. 
