THE  AMERICAN 
JOURNAL  OF  PHARMACY. 
JANUARY,  1880. 
ON  THE  PRESENCE  OF  TANNIN  IN  GENTIAN. 
By  John  M.  Maisch. 
Read  at  the  Pharmaceutical  Meeting  December  15,  1879; 
In  February,  1876,  the  writer  read  a  paper  on  this  subject,  in  which 
he  believed  to  have  proven  that  gentian  root  contains  no  tannin,  and 
that  the  dark  coloration  produced  with  iron  salts  is  due  to  gentianic  or 
gentisic  acid.  These  conclusions  seemed  to  follow  from  the  following 
observations : 
1.  That  the  infusion  of  gentian,  sufficiently  diluted  so  as  to  be  filtered 
from  the  suspended  pectin  compounds,  yields  with  gelatin  a  slight  pre- 
cipitate which  after  having  been  washed  with  cold  water  is  not  colored 
black  or  dark  green  by  ferric  chloride,  but  merely  acquires  the  brownish 
color  of  ferric  salts. 
2.  That  the  cold  infusion  of  gentian,  treated  for  24  hours  with  a  large 
fragment  of  fresh  hide,  showed  not  the  slightest  diminution  in  the  dark 
coloration  imparted  by  ferric  chloride. 
These  experiments  were  supplemented  by  the  following  one  per- 
formed by  Mr.  E.  L.  Patch,  of  Boston,  and  reported  in  the  "Amer. 
Jour.  Pharm.,"  1876,  p.  188.  The  alcoholic  solution  of  the 
etherial  extract  of  gentian  yielded  with  ferric  salts  dark  green  color- 
ations, but  on  diluting  it  with  water  and  filtering  from  the  precipitated 
resin,  etc.,  the  clear  liquid  yielded  no  precipitate  with  gelatin,  which 
should  have  occurred  if  tannin  had  been  present. 
In  1877  Mr.  Jules  Ville  published  an  essay,  which  was  reviewed  in 
the  "Amer.  Jour.  Pharm.,"  1877,  P*  4^9  i  arrived  at  the  conclusion 
that  tannin  is  present  in  gentian,  because 
1.  The  infusion  produces  a  slight  precipitate  with  gelatin,  and 
2.  The  infusion  treated  with  fresh  hide,  February  i6th,  gradually 
gave  fainter  reactions  with  ferric  chloride,  until  on  April  12th  the 
infusion  was  insensible  to  the  action  of  the  reagent  named. 
