Am.  Jour.  Pharm, 
May,  1890. 
Tannin  in  Quercus  Alba. 
237 
eolation  to  proceed  only  so  long  as  the  percolate  showed  a  deep  red- 
brown  color.  This  concentrated  alcoholic  solution  was  distilled 
under  reduced  pressure  to  a  volume  of  about  250  cc,  the  alcohol 
being  further  removed  over  sulphuric  acid  in  a  vacuum  desiccator. 
This  extract  was  then  dissolved  m  tepid  water  and  the  solution 
filtered  from  a  reddish-brown  substance  which  remained  undissolved  ; 
(but  which  redissolved  readily  in  sodium  hydrate  or  in  alcohol) 
while  to  the  filtrate  additional  water  was  added  until  no  further 
precipitation  occurred.  The  solution  was  again  filtered  and  when 
perfectly  clear  surrounded  with  ice;  when  there  separated  an  addi- 
tional amount  of  the  same  reddish-brown  substance  as  before  and 
which  indeed  it  is  difficult  to  remove.  The  tannin  was  now  precipi- 
tated from  solution  by.  means  of  sodium  chloride.  In  previous 
experiments  it  was  found  that  the  amount  of  salt  required  to  saturate 
the  tannin  solution  was  0-3512  gm.  for  1  cc.  The  sodium  chloride, 
previously  calculated,  was  divided  into  five  equal  parts  and  added  in 
separate  portions,  slowly  but  with  constant  stirring  to  the  solution, 
which  was  surrounded  by  a  freezing  mixture.  In  this  manner  five 
fractions  of  tannin  were  obtained.  The  original  aqueous  solution, 
before  addition  of  sodium  chloride,  was  of  a  dark  red  color  as  was 
also  the  first  fraction  of  tannin.  The  solution  as  well  as  the  succeed- 
ing fractions  of  tannin  became  lighter  in  color,  the  last  being  of  a 
yellow  color.  Each  one  of  the  precipitated  tannins  was  now 
separately  dissolved  in  tepid  water ;  filtered  from  some  of  the  same 
reddish-brown  substance  as  observed  before,  and  water  was  added 
until  precipitation  ceased.  The  solutions  were  filtered  and  the 
tannins  again  precipitated  with  sodium  chloride,  but  were  imme- 
diately taken  up  by  means  of  acetic  ether.  Between  the  aqueous 
and  ethereal  solutions  there  was  suspended  some  of  the  same  reddish- 
brown  substance,  a  part  of  which  adhered  to  the  sides  of  the  separ- 
atory  funnel.  The  acetic  ether  was  removed  from  the  tannins 
in  a  vacuum  desiccator  over  sulphuric  acid.  They  were  again 
separately  taken  up  with  tepid  water  and  additional  water 
added  as  before ;  also  extracted  with  acetic  ether  and  the  ether 
removed  as  previously.  By  these  repeated  methods  of  purification 
five  pure,  though  small,  fractions  of  tannin  were  obtained.  All  of 
them  at  first  dissolved  in  warm  water,  but  in  a  short  time,  they  all 
showed  signs  of  having  undergone  more  or  less  decomposition.  The 
combustions  made  of  the  separate  fractions  showed  considerable 
