Am.  Jour.  Pharni.  \ 
December,  1894.  j 
Riibus  Villosus. 
585 
percolate,  was  shaken  with  acetic  ether,  which,  as  before,  extracted 
only  a  very  small  amount  of  tannin. 
Acetic  ether  is  used  for  the  extraction  of  most  tannins  from  their 
aqueous  solutions,  and  on  account  of  the  small  yield  in  the  above 
experiment,  the  watery  liquid  was  tested  for  tannin  with  ferric 
chloride,  lead  acetate  and  gelatin,  all  of  which  gave  abundant  pre- 
cipitates, thus  confirming  the  presence  of  this  principle,  and  demon- 
strating the  insolubility  of  the  latter  in  acetic  ether,  when  applied 
to  the  aqueous  solution. 
When  this  evidence  of  the  inefificacy  of  acetic  ether  was  estab- 
lished, the  whole  amount  of  the  tannin-containing  liquid  was 
manipulated  as  follows :  The  solution  was  divided  into  two  equal 
portions,  one  of  these  was  exactly  precipitated  with  lead  acetate, 
the  lead  compound  collected  on  a  filter,  thoroughly  drained,  then 
stirred  into  the  retained  portion,  and  the  mixture  filtered. 
The  much  lighter-colored  liquid  so  obtained  was  concentrated 
under  reduced  pressure  to  about  one-fourth  its  volume  and  again 
filtered.  After  agitation  with  successive  portions  of  ether,  it  was 
further  concentrated,  refiltered,  and  distilled  under  the  above  condi- 
tions to  dryness. 
The  residue  had  a  brownish-yellow  color  and  was  but  sparingly 
soluble  in  ether,  alcohol  or  acetone.  To  separate  any  remaining 
traces  of  lead,  the  residue  was  treated  with  distilled  water,  which 
readily  effected  solution  of  the  greater  part,  the  aqueous  solution 
filtered,  saturated  with  hydrogen  sulphide,  refiltered  and  distilled  to 
dryness  under  diminished  pressure. 
Again,  as  before,  the  tannin  was  obtained  as  a  hard,  resinous  resi- 
due. 
As  it  is  customary  to  recognize  the  purity  of  a  tannin  to  a  certain 
extent  by  obtaining  it  in  a  porous  or  "  puffed  up  "  condition,  fre- 
quent attempts  were  made  to  procure  this  one  in  that  form  by  dis- 
solving the  material  in  ether,  alcohol  and  acetone  alone,  and  in  mix- 
tures of  alcohol  and  acetone,  and  rapidly  distilling  off  the  solvents 
in  a  vacuum  apparatus;  but  all  efforts  to  this  end  were  futile. 
The  substance  was  then  powdered  and  dissolved  in  a  small  quan- 
tity of  distilled  water.  This  solution  was  mixed  with  five  times  its 
volume  of  alcohol,  sp.  gr.  -794,  which  produced  a  copious  precipi- 
tate of  a  yellowish  mucilage,  which  was  readily  soluble  in  water  and 
precipitable  by  both  neutral  and  basic  lead  acetate,  but  not  by  gela- 
