AGRICULTURAL  BULLETIN 
OF  IHE 
STRAITS 
AND 
FEDERATED  MALAY  STATES. 
No.  12.]  DECEMBER,  1903.  [^^ol.  II. 
THE  CHEMISTRY  OF  RUBBER, 
P)V  P.  J.  Burgess. 
During  the  last  ten  years  the  cultivation  of  rubber  in  plantations 
has  become  well  established  in  the  Malay  Peninsula,  and  the  cul- 
tivation now  bids  fair  to  be  of  great  profit  to  all  interested  in  it  and 
of  indirectly  being  a distinct  step  in  the  development  of  the  re- 
sources of  the  Peninsula. 
At  the  present  time  many  of  the  trees  in  the  earlier  planted 
areas  are  of  sufficient  age  for  yielding  rubber,  and  I believe  that 
an  account  of  the  chemistry  of  the  latex  of  the  rubber,  and  of  the 
extraction  of  the  rubber  from  the  latex,  will  prove  of  interest  and 
use.  I shall  at  first  confine  myself  to  an  account  of  the  latex  and 
rubber  from  Hevea  braziliensis  or  Para  rubber,  and  then  afterwards 
point  cut  the  differences  shewn  by  other  kinds  of  rubber. 
The  latex  when  freshly  collected  is  a white  or  faintly  yellow 
milky  liquid  with  a distinct  and  pleasing  aromatic  odour.  In  reac- 
tion it  is  alkaline  and  in  this  it  differs  from  the  latices  from  Ficus 
elastica,  Castilloa  and  others,  which  are  acidic.  Under  the  micros- 
cope it  is  seen  to  consist  of  globules  floating  in  a clear  liquid.  The 
globules  are  exceedingly  minute  being  from  one  to  two  thousandths 
of  a millimetre  in  diameter.  They  are  regular  in  size  and  are  in 
constant  and  rapid  movement.  If  the  latex  be  filtered  through  a 
sufficiently  fine  filter — such  as,  for  instance,  a Pasteur-Chamberlain 
filter  tube — these  globules,  which  are  globules  of  rubber,  can  be 
separated,  and  the  liquid  that  passes  through  is  clear,  pale  yellow, 
alkaline  in  reaction,  slightly  sweet  in  taste,  and  has  an  odour  very 
similar  to  that  of  the  oriorinal  latex. 
O 
I wish  at  the  outset  to  emphasize  this  separation  of  the  latex 
into  two  parts — the  solid  or  pseudo-solid  portion  shewn  as  glo- 
bules under  the  microscope,  and  the  liquid  menstruum  in  which  the 
globules  are  suspended;  and  the  fact  may  be  at  once  stated  that 
the  problem  to  be  solved  in  the  preparation  of  rubber  is  to  separate 
this  liquid  from  the  solid  as  perfectly  as  possible — the  liquid  car- 
ries in  solution  all  those  impurities  which  can  possibly  be  removed 
in  the  manufacture  of  rubber  from  latex, 
