Am aJXiwo*™" }       Caramclization  in  Rivas's  Test.  159 
aldehyde  in  aqueous  solutipn  is  warmed  with  potassium  hydroxide, 
the  liquid  becomes  yellow  and  after  a  time  reddish-brown  amor- 
phous masses  are  precipitated,  "  with  the  simultaneous  production 
of  a  peculiar  odor."  The  brown  substance  formed  is  called  "  alde- 
hyde-resin." 
This  method  of  explanation  involves  no  new  or  improbable  ideas. 
In  fact,  this  behavior  of  aldehydes  is  given  as  characteristic  of 
them,  in  the  usual  text-books  of  organic  chemistry.19  Further, 
this  explanation  is  consistent  with  the  facts  in  the  case,  even  sup- 
plying some  explanation  for  the  bleaching  action  of  molecular 
oxygen.  For  aldehyde-compounds  would  be  expected  to  oxidize. 
It  is  also  in  accordance  with  the  experience  of  every  chemist  who 
has  added  alkalies  to  alcohol,  before  distilling  it  to  free  it  from 
aldehydes.  The  yellow  to  brown  colors  produced  in  alcohol  under 
these  conditions  are  also  discharged  by  acids.  And  lastly,  it 
explains  the  formation  of  a  brown  color  in  the  almost  colorless 
aqueous  layer  obtained  in  Marsh's  Test  applied  to  a  straight 
whiskey,  when  this  layer  had  been  separated  from  the  whiskey  and 
then  treated  with  alkali  as  described  in  the  early  part  of  this  paper. 
For  this  aqueous  layer  contains  aldehydes. 
Milk-sugar  gives  similar  results.  An  explanation  may  be  found 
in  this  case,  too,  without  recourse  to  the  assumption  of  carameliza- 
tion.  Milk-sugar  is  well  known  to  be  readily  hydrolyzed  with  the 
destruction  of  the  monocarbonyl  bond, 
C6Hu05<  OC6Hn05<  +  H20  =  C6H1206  +  C6H12Oe, 
yielding-  d-glucose  and  d-galactose.  It  is  also  well  known  that 
alkalies,  or  rather  hydroxyl  ions,  catalyze  hydrolysis.  It  may  well 
be,  then,  that  in  Rivas's  Test  the  milk-sugar  is  first  partly  hydrolyzed 
into  glucose  which  then  reacts  with  the  alkali  as  suggested  above, 
with  the  production  of  the  dark  colored  condensation  products. 
I  do  not  wish  to  be  understood  as  omitting  the  formation  of 
aldols  as  a  part  of  these  condensations.  Just  as  acetaldehyde  forms 
aldol,  so  other  aldehydes  may  be  expected  to : 
CH3.C<fH+  H.CH2C</H=CH3C(/— CH2C/H  aldol. 
19  Holleman's  Organic  Chemistry,  Tr.  by  Walker,  N.Y.,  1006,  p.  135 ; 
Bernsthen's  Organic  Chemistry,  p.  144. 
