180  Color  in  Liquor  Calcis  Saceharratus.        |  ^""kpHrisss 
allowed  to  stand  undisturbed  for  a  fortnight.  .  On  examination  at  the 
end  of  that  period,  it  was  found  that  on  the  surface  of  the  liquid,  where 
it  was  subjected  to  the  influence  of  the  air,  there  was  a  highly  colored 
stratum  about  1  inch  deep,  while  the  rest  of  the  liquor  remained  unal- 
tered. 
These  experiments  appear  to  prove  that  the  development  of  color  in 
liq.  calcis  sacch.  is  due  entirely  to  exposure  to  atmospheric  air,  and  that 
light  and  heat  are  not  concerned  in  the  action.  This  explains  the  fact, 
already  mentioned,  that  the  second  portion  of  the  filtrate,  which  was 
longer  exposed  to  the  air,  was  more  highly  colored.  I  have  made  an 
extensive  series  of  experiments  with  a  view  to  determine  the  nature  of 
the  chemical  changes  to  which  the  coloration  is  due,  but  owing  to  the 
very  limited  time  at  my  disposal,  these  are  very  incomplete  and  incon- 
clusive, and  would  require  consi  lerable  verification.  With  that  proviso 
I  give  a  few  results  which  may  be  taken  for  what  they  are  worth. 
It  is  well  known  that  a  solution  of  cane  sugar  when  allowed  to  stand 
becomes  partially  changed  into  grape  sugar  and  levulose  according  to 
the  following  equation  — 
^'12^22011  H-HjO^CgHipg-j-CeHiPg. 
By  the  action  of  the  alkalies,  grape  sugar  is  rapidly  decomposed  with 
production  of  a  deep  brown  color,  and  my  first  idea  was  that  this 
reaction  explained  the  coloration.  A  portion  of  the  liquor  was  pre- 
cipitated by  passing  a  stream  of  carbonic  acid  gas  which,  by  the  way, 
only  slowly  separates  the  lime.  The  whole  of  the  coloring  matter  was 
thus  precipitated,  and  on  testing  the  clear  solution  with  Fehling's  re- 
agent no  reduction  took  place,  indicating  absence  of  grape  sugar.  On 
this  point  I  have  more  to  say  presently.  My  next  idea  was  that  pos- 
sibly the  coloration  might  be  due  to  production  of  amorphous  sugar 
which,  as  is  well  known,  gives  the  yellowish-brown  tint  to  the  mother 
liquor  or  golden  syrup  of  the  sugar  refineries.  To  test  this  theory,  a 
small  proportion  of  golden  syrup  was  added  to  a  portion  of  the  fresh 
liquor,  which  was  allowed  to  stand  for  some  time  and  then  precipitated 
by  a  stream  of  CO2.  Under  these  circumstances  the  coloring  matter 
was  not  precipitated,  and  the  amorphous  sugar  theory  was  therefore 
abandoned.  On  reconsidering  my  first  theory  it  occurred  to  me  that 
the  reason  w^hy  I  did  not  discover  grape  sugar  in  the  liquor,  was  that 
it  had  been  decomj)osed  by  the  alkaline  solution  as  rapidly  as  it  had  been 
formed.    Two  grains  of  impure  grape  sugar  were  added  to  1  ounce  of 
