Am.  Jour.  Pharm.\ 
February,  1897.  J 
North  American  Coniferce. 
95 
were  collected  in  1896  were  taken  from  similar  trees  for  the  especial 
purpose  of  determining  their  relative  tannin  value. 
Preparation. — For  the  purpose  of  investigating  its  composition 
and  properties,  a  considerable  quantity  of  the  tannin  was  prepared 
by  extracting  hemlock  bark  with  acetone.  The  solvent  was  recovered 
by  distillation  and  the  syrupy  residue  was  poured  into  several  times 
its  bulk  of  water;  the  insoluble  resin  and  anhydrides  were  separated 
by  agitation  with  paper  pulp  and  filtration.  The  clear  aqueous  liquid 
was  saturated  with  sodium  chloride  and  shaken  with  acetic  ether, 
which  removed  the  tannin,1  the  solvent  in  this  case  being  removed 
by  distillation  under  reduced  pressure.  The  residue  was  redissolved 
in  water,  salt  added  and  the  tannin  again  removed  by  acetic  ether, 
and  the  operation  repeated  until  a  tannin  resulted  which  formed 
a  clear  solution  with  water.  It  was  then  treated  with  absolute 
ether,  in  which  it  was  insoluble,  and,  after  removal  of  the  ether, 
dried. 
Properties  and  Composition. — The  product  was  a  reddish  porous 
powder,  completely  and  readily  soluble  in  water  and  in  alcohol.  A 
1  per  cent,  solution  gave  the  following  reactions : 
Reagent. 
Hemlock  Tannin. 
Chestnut  Oak 
Tannin. 
Gallotannic  Acid. 
Ferric  chloride 
and 
Brownish-green 
color  and  ppt. 
Green  color 
and  ppt. 
Blue  color 
and  ppt. 
Ammonium 
hydrate. 
Purple  color 
and  ppt. 
Purple  ppt. 
Purple  ppt. 
Ammonio-ferric 
sulphate. 
Brownish-green 
color  and  ppt. 
Green  color 
and  ppt. 
Blue  color 
and  ppt. 
Calcium  hydrate. 
Pinkish  ppt., 
turning  red. 
Precipitate 
turning  pink. 
Precipitate 
turning  blue. 
Bromine  water. 
Yellow  ppt. 
Yellow  ppt. 
No  ppt. 
A  study  of  the  decomposition  products  of  hemlock  tannin  was 
made  in  the  usual  way.  The  product  resulting  from  the  action  of 
heat  on  a  solution  of  the  tannin  in  glycerin  was  identified  as 
1  It  has  since  been  found  that  methyl  acetate  with  salt  answers  the  purpose 
of  an  immiscible  solvent,  for  the  removal  of  tannin,  equally  as  well  as  ethyl 
acetate,  and  is  much  cheaper. 
