184     Colored  Reactions  oj  Phenols  with  Carbohydrates,  {AmAirii*"^rm* 
COLORED  REACTIONS  OF  PHENOLS  WITH  CARBO- 
HYDRATES. 
By  Anton  Ihl. 
These  reactions  are  produced  by  adding  the  pulverized  carbohydrates 
to  an  alcoholic  solution  of  the  phenol. 
a-Naphthol  gives  with  cane-sugar  at  a  gentle  heat  a  splendid  red- 
dish violet  color,  which  disappears  on  the  addition  of  water;  with 
milk-sugar  a  fine  violet  and  with  starch  a  dark  red  violet. 
/9-Naphthol  gives  with  cane-sugar  a  yellow,  which  on  prolonged 
boiling  turns  a  dark  greenish  yellow  with  a  greenish  fluorescence; 
with  milk-sugar,  a  pure  yellow  without  fluorescence;  with  glucose,  a 
yellowish  green  color  with  a  strong  green  fluorescence ;  with  dextrin, 
a  yellowish;  with  arabin,  a  light  yellow;  and  with  starch,  a  faint 
yellow. 
Resorcin  gives  with  cane-sugar  an  intense  fiery  red,  which  retains 
its  color  on  dilution  with  water;  with  milk-sugar,  glucose,  dextrin, 
arabin,  and  starch,  yellowish  red. 
Pyrogallic  acid  gives  reactions  very  similar  to  those  of  resorcin. 
Phloroglucin  gives  with  cane-sugar,  on  gentle  heating,  an  intense 
yellowish  red  color,  which  became  a  fine  light  yellow  on  dilution  with 
water ;  with  milk-sugar  a  reddish  brown ;  with  glucose,  a  yellowish 
red;  with  dextrin,  a  slight  dirty  yellow;  with  arabin,  on  prolonged 
heating,  an  intense  cochineal-red  pigment,  which  is  permanent  on  the 
addition  of  water. 
The  phenols  are  also  well  adapted  for  the  detection  of  woody  mat- 
ters. They  are  used  in  an  alcoholic  solution,  mixed  with  hydrochloric 
or  sulphuric  acid,  and  applied  either  cold  or  hot  to  the  paper  or  wood 
in  question. 
Solution  of  orcin  mixed  with  hydrochloric  acid  gives  a  splendid 
dark-red  on  wood ;  upon  paper  containing  wood-stuff  it  gives  a  dark 
red- violet  spot.    Pure  cellulose-paper  undergoes  no  change. 
Resorcin  with  alcohol  and  hydrochloric  acid  colors  wood-stuff  paper 
a  violet-blue  in  a  short  time.  Pure  cellulose-paper  remains  unaf- 
fected. Resorcin  with  alcohol  and  sulphuric  acid  (one  vol.  alcohol, 
one-third  vol.  sulphuric  acid),  when  warm,  colors  wood-paper  or  wood 
a  dark  violet-blue.    Pure  cellulose-paper  is  colored  an  onion-red. 
a-Naphthol  in  alcohol  and  hydrochloric  acid  colors  wood-stuff  paper 
and  wood  greenish. 
