AmfuZ%TTm'}        Tannin  of  Punica  Granatum.  281 
with  water,  the  solution  filtered  and  again  shaken  with  ether,  which 
removed,  and  left  upon  evaporation,  crystals  which  gave  the  follow- 
ing reactions  for  gallic  acid  : 
Ferric  chloride,  dark-blue  color. 
Sodium  carbonate,  green  color. 
Sulphuric  acid,  purple  red  color. 
The  aqueous  layer,  from  which  the  gallic  acid  had  been  removed 
by  ether,  was  agitated  with  acetic  ether.  The  several  quantities  of 
this  liquid  so  applied,  were  mixed,  and  distilled,  under  reduced 
pressure,  to  dryness.  The  residue  was  treated  with  a  mixture  of 
two  volumes  of  alcohol  and  one  volume  of  ether,  the  insoluble  part 
was  separated  by  nitration  and  the  filtrate  distilled  to  dryness  under 
diminished  pressure. 
By  repeating  this  process  several  times,  a  porous,  red-brown  tan- 
nin was  finally  obtained.  This  was  further  purified  by  solution  in 
water,  and  nitration  through  its  lead  compound  obtained  by  precipi- 
tation of  part  of  the  solution  with  lead  acetate. 
From  the  much  lighter  colored  filtrate  acetic  ether  removed  a 
purer  tannin. 
The  aqueous  layer,  from  which  the  gallic  acid  and  some  tannin 
had  been  removed  by  ether  and  acetic  ether  respectively,  was  now 
completely  precipitated  with  basic  lead  acetate.  The  mixture  was 
filtered.  The  precipitate  produced  by  the  lead  salt  was  suspended 
in  water  and  decomposed  by  hydrogen  sulphide.  Lead  sulphide 
was  separated  by  filtration  and  the  filtrate  warmed  to  expel  the 
excess  of  the  gas,  after  which  it  was  cooled,  saturated  with  sodium 
chloride  and  agitated  with  successive  portions  of  acetic  ether.  This 
solvent  removed  the  tannin,  and,  upon  being  recovered  under 
reduced  pressure,  left  the  same  in  a  purer  condition  than  when 
obtained  by  the  preceding  methods. 
All  the  tannins  were  further  purified  by  solution  in  a  mixture  of 
three  parts  by  volume  of  ether  and  one  part  by  volume  of  alcohol, 
filtering  and  distilling  under  reduced  pressure,  whereby  they  were 
changed  into  a  more  or  less  porous  form. 
All  of  these  tannins  were  found  to  be  the  same,  as  shown  by  the 
following  reactions  of  their  one  per  cent,  solutions,  from  which 
gallic  acid  had  previously  been  removed  by  agitation  with  ether. 
For  comparison,  the  reactions  of  gallotannic  acid  are  placed 
alongside  of  those  obtained. 
