Am.  Jour.  Pharm  1 
May,  1890.  / 
Tannin  in  Quercus  Alba. 
239 
acid  in  that  this  color  was  replaced  by  a  yellow  upon  the  addition 
of  hydrochloric  acid.  A  portion  of  the  mass  remaining  from  the 
ethereal  solution  deposited  a  slightly  yellowish  amorphous  sub- 
stance upon  sublimation,  producing  with  ferric  chloride  a  deep  red 
color.  Another  portion  with  ferric  chloride  gave  a  green  color, 
which  immediately  changed  to  a  yellowish-brown  upon  the  addi- 
tion of  sodium  bicarbonate,  having  a  blue  fluorescence. 
A  third  portion  of  the  tannin  was  heated  at  ioo°  C  ,  with  a  I  per 
cent,  solution  of  hydrochloric  acid  for  six  hours  in  a  sealed  tube.  A 
reddish-brown  scaly  substance  separated  (soluble  in  alkalies  and  in 
alcohol).  The  filtered  clear  yellow  solution  had  a  slight  blue  fluo- 
rescence. It  was  shaken  up  with  ether  and  the  ether  removed  by 
spontaneous  evaporation.  A  light  yellowish  amorphous  substance 
remained,  having  a  bark-like  odor,  producing  with  sulphuric  acid 
a  greenish-yellow  color,  which  became  red  upon  warming,  and  on 
the  addition  of  sodium  hydrate,  the  color  disappeared,  but 
reappeared  on  adding  a  slight  excess  of  alkali.  If  ammonia  be  used 
in  this  test,  in  addition  to  the  above  color,  a  decided  fluorescence  is 
observed.  The  aqueous  solution  was  now  deprived  of  ether  by  boil- 
ing, and  then  treated  with  Fehling's  solution,  which  was  reduced.  A 
portion  also  gave  with  ferric  chloride  an  olive  green  color  ;  with 
acetate  of  lead  a  flocculent  precipitate ;  with  sodium  hydrate  a  red 
brown  color  by  transmitted  light  and  a  blue  by  reflected  light. 
The  aqueous  solution  of  the  tannin  of  Quercus  alba  is  light  yellow 
in  color  ;  reddens  blue  litmus  and  gives  also  the  following  reactions  : 
With  Fe2Cl6,  an  olive  brown  color  possessing  a  slight  fluorescence  ;  in  strong 
solutions  a  dark  olive  brown  precipitate. 
With  alkalies,  a  deep  red  color,  having *also  a  decided  blue  fluorescence. 
With  Pb  (C2H302)2,  a  flocculent  precipitate  (hardly  white). 
With  K6Fe2  (CN)12  +  NH3,  a  deep  red  color. 
With  AgN03,  on  application  of  heat,  a  reduction  of  metallic  silver. 
With  Fehling's  solution,  on  application  of  heat,  a  reduction  of  metallic  copper. 
With  uranium  acetate,  a  red  brown  precipitate,  redissolving  in  acetic  acid. 
From  these  observations  it  will  be  seen  that  the  tannin  of  Quercus 
alba  yields  upon  sublimation  a  crystalline  principle  resembling  some- 
what pyrocatechin.  Upon  atmospheric  oxidation  it  gives  the  insolu- 
ble red  or  phlobaphene  ;  and  upon  fusing  some  of  the  tannin  with 
potassium  hydrate  gives  a  phenol  similar  to  protocatechuic  acid. 
The  alkaline  solutions  of  the  tannin  upon  certain  conditions 
possess  a  blue  fluorescence.    This  fluorescent  principle  was  per- 
