96  North  American  Conifer  a,  {AFebr°uarry!?8^m- 
catechol.  Boiling  hydrochloric  acid  containing  2  per  cent,  of  HC1 
gas,  resolved  the  tannin  into  an  amorphous,  reddish-brown,  in- 
soluble phlobaphene  and  soluble  protocatechuic  acid.  The  phlo- 
baphene  was  of  the  same  character  as  that  obtained  from  the 
tannins  of  several  oak  barks.  When  heated  with  fused  potassium 
hydrate  the  tannin  yielded  protocatechuic  acid.  Although  the 
above  reactions  and  decomposition  products  indicated  a  great 
similarity  between  the  tannins  of  the  barks  of  the  hemlock  and 
oaks,  an  ultimate  analysis  was  made  in  order  to  further  establish 
their  relationship.  The  results  which  were  obtained  show  that 
the  tannins  from  these  two  sources  are  very  closely  related,  if, 
indeed,  not  identical.  For  comparison,  the  figures  which  represent 
the  composition  of  chestnut  oak  bark  tannin,  gallotannic  acid  and 
the  average  composition  of  the  tannins  from  nine  species  of  oak 
bark  are  given  : 
Average  on 
Chestnut  Oak  Tannins  from  Nine  Gallotannic 
Hemlock  Tannin.        Tannin.  Species  of  Oaks.  Acid. 
Carbon  60-09  59*69  59*79  52*17 
Hydrogen  5-18  5*06  5*08  3*10 
Oxygen  3473  35-25  35-13  44*73 
IOO'OO  IOO'OO  IOO'OO  IOO'OO 
The  several  tannins  used  in  the  combustions  were  dried  at  1200  C. 
The  conclusion  from  this  study  of  the  properties  and  composition 
of  hemlock  tannin  is  that  it  is  identical  with  the  other  tannins 
of  this  natural  order,  which  have  thus  far  been  studied  by  us,  as 
well  as  with  the  tannin  of  oak  bark,  and  a  number  of  others  from  a 
variety  of  sources. 
The  only  other  investigation  of  hemlock  tannin  on  record  was 
made  by  Boettinger1,  in  1884,  who,  by  precipitating  a  commercial 
extract  of  hemlock  bark  with  bromine,  and  estimating  the  halogen  in 
the  product,  deduced  the  formula  C20HuBr4O10  from  which  he  con- 
cluded that  the  tannin  had  a  composition  expressed  by  the  formula 
C20H18O10.  Such  a  formula  would  require  the  following  percentage 
composition  : 
C  .  .  '  57'4i 
H  ^  .  ,  -  ,  *  4'3i 
O   •  38-28 
IOO'OO 
1  Berichte  der  deut.  chem.  Gesell.,  17,  1041  and  1123. 
