$o6 
Tannin  of  Ceriops  Candolleana. 
{ 
Am.  Jour.  Pharm. 
October,  1897. 
deep  port  wine  coloring  to  water,  and  contains  large  quantities  of 
both  coloring  matter  and  tannin.  On  these  two  substances  depends 
the  use  of  the  bark  for  both  dyeing  and  tanning.  It  is  by  far  the 
most  valuable  one  of  the  mangrove  barks  for  tanning.  The  claim 
is  made2  that  it  imparts  a  fine  red  color  to  leather.  It  may  be  said, 
in  regard  to  this,  however,  that  tanners  usually  object  to  a  reddish 
color  imparted  by  tanning  materials,  and  the  objection  heretofore  to 
all  mangrove  barks  has  been  the  tendency  they  have  to  produce  a 
red  color  and  a  soft  leather.  Another  real  objection  to  the  man- 
grove extract  sent  from  a  tropical  climate  has  been  noted  by  Mr. 
Ridley,  who  says  the  stuff  has  generally  been  so  abominably  pre- 
pared that  no  one  will  look  at  it.  At  the  present  time  attempts 
are  being  made  to  manufacture  a  good  quality  of  extract  in  southern 
India  and  Borneo  for  export.3 
The  wood  is  used  in  the  province  of  Sind  for  the  knees  of  boats 
and  several  other  purposes,  and  in  Lower  Bengal  for  house  posts 
and  for  firewood. 
Each  of  the  two  samples  yielded  the  following  percentages  of 
moisture,  ash  and  tannin  : 
It  will  be  seen  from  the  tannin  percentages  that  Ceriops  well  de- 
serves the  reputation  it  has  for  being  the  most  valuable  one  of  the 
mangroves.  The  per  cent,  of  tannin  is  more  than  is  usually  found 
in  barks,  and  is  perhaps  only  equalled  by  the  wattle  barks  of  Aus- 
tralia. The  differences  of  both  tannin  and  ash  in  the  above 
samples  are  considerable,  but  not  more  than  is  found  in  our  oaks 
when  collected  at  different  seasons  of  the  year. 
A  quantity  of  tannin  was  prepared  from  the  Bengal  sample.  It 
was  thoroughly  purified  and  submitted  to  elementary  analysis, 
yielding  the  following  percentage  results  : 
Carbon  61*13 
Hydrogen  5*29 
These  figures,  with  the  reactions  towards  iron  salts,  bromine 
water  and  calcium  hydrate,  prove  it  to  belong  in  the  class  of  oak 
bark  tannins. 
2  Watt,  Dictionary  of  the  Economic  Products  of  India,  Vol.  II,  p.  261. 
3  Kew  Bulletin  for  February  and  March,  1897,  contains  a  report  by  Professor 
Hummel  on  the  value  of  Ceriops  bark  for  dyeing  purposes. 
Moisture. 
Sample  from  Bengal  .  .  .13*70 
Sample  from  Singapore  .  .  13*34 
Ash  in 
absolutely 
dry  sample. 
2COO 
23-07 
