AGRICULTURAL BULLETIN 
OF THE 
STRAITS 
AND 
FEDERATED MALAY STATES. 
No. 12.] DECEMBER, 1903. [Vol. II. 
THE CHEMISTRY OF RUBBER, 
By 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 coniine myself to an account of the latex and 
rubber from Hevea brasiliensis or Para rubber, and then afterwards 
point out 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 original latex. 
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, 
