CARAMEL  COLORS. 
441 
CARAMEL  COLORS. 
To  the  Editor  of  the  Chemical  News. 
Sir: — Under  the  "  Notes  and  Queries"  in  your  valuable 
paper,  (No.  387,)  I  happen  to  find  one  concerning  caramel.  Per- 
haps the  following  may  be  of  use  to  your  correspondent : — 
The  manufacture  of  caramel  (coffee  finings,  as  it  is  often  termed 
in  London,)  is  kept  a  secret  on  this  account,  that  neither  cof- 
fee-roasters, nor  dealers  in  groceries,  nor  brewers,  may  have,  or 
at  least  are  presumed  not  to  have,  any  in  their  possession — the 
Excise  prohibiting  it.  Here  in  London  it  is  made  by  roasting 
sugar  of  coarse  description  in  cylinders  similar  to  those  used  for 
roasting  coffee,  chicory  and  cocoa;  this  yields  a  very  inferior 
preparation  both  for  coloring  as  well  as  admixture  with  coffee. 
So  prepared,  it  contains  assamar  and  other  pyrogen etic  pro- 
ducts which  are  very  bitter.  On  the  continent  apples  of  inferior 
description  are  treated  as  described,  yielding  a  product  superior 
to  that  obtained  from  sugar.  Sugar,  however,  is  the  only  fit 
material  to  prepare  caramel,  and  for  this  purpose  the  sugar  is 
best  heated  in  capacious  roomy  vessels  made  of  copper,  (in 
Vienna  copper  lined  with  silver  is  preferred,)  the*  vessel  contain- 
ing the  sugar  being  placed  in  an  oil  bath*  containing  a  ther- 
mometer to  indicate  the  temperature.  The  latter  must  not  be 
below  410°  nor  above  428°  Fahr.  The  heating  of  the  sugar  is 
continued  as  long  as  aqueous  vapors  are  given  off.  The  crude 
caramel  so  obtained  is  best  purified  by  being  placed  upon  a 
parchment  paper  dialyser,  which  is  placed  on  water.  The  unde- 
composed  sugar  and  intermediate  compounds  are  thus  got  rid  of; 
they  dissolve  out  with  facility,  and  what  remains  on  the  filter  is, 
weight  for  weight,  five  times  as  strong  in  coloring  matter  as  the 
crude  caramel.  While  the  sugar  is  being  exposed  to  heat,  it  is 
preferable  to  stir  it  with  a  spatula. 
Another  mode  of  obtaining  a  pure  caramel,  free  from  bitter 
produce,  assamar  and  the  like,)  is  to  heat  the  sugar  as  above, 
and  to  treat  the  powdered  caramel  with  alcohol,  (pure  methylated 
spirits,)  to  digest  it  for  three  to  four  hours  therewith,  and  repeat 
*  A  mixture  of  tin  and  lead  is  sometimes  used,  just  made  so  as  to 
remain  fluid  at  from  412°  to  430°  Fahr.  ;  some  bismuth  is  added. 
