347 
believes in the likelihood of the production of substitute for the real 
article, or has seen a sample of it, and at the lower range of prices for 
all kinds of rubber and the increasing supplies the danger now from 
this source is more remote than ever. 
Queensland Agricultural Journal, June 1908. 
TREATMENT OF LATEX IN THE 
PREPARATION OF RUBBER. 
M. Kelway BAMBEK, The Laboratory , Colombo, Ceylon . 
A point of considerable importance in the manufacture of Planta- 
tion rubber is to obtain, not only purity, but constant uniformity in 
the finished product. 
At present there are almost daily variations in appearance, due to 
causes which cannot easily be overcome, such as weather, age of trees 
being tapped, and the bringing of new trees into bearing, all of which 
affect the colour and clearness of the dried rubber. 
The discolouration is due to oxidation of soluble organic bodies 
allied to tannin in the latex water, by means of an oxidising enzyme, 
and is intensified by a warm temperature and exposure to the air. 
Thorough washing of the freshly coagulated caoutchouc will re- 
move'much of the soluble matter with the enzyme, but it is difficult or 
impossible to remove it all, and other means have to be adopted to 
prevent the darkening on drying which almost invariably occurs. 
This is done by destroying the enzyme by means of heat before 
oxidation occurs, with the result that the rubber dries of a clear pale 
yellow colour, and of perfect uniformity from day to day. 
The beating can be done in different ways before or after coagula- 
tion. 
1st. By passing steam into the bulked latex until the temperature 
reaches 80° C or 167° F, and maintaining this temperature for 15 
minutes or longer, according to the thickness of the rubber. 
2nd. By immersing the biscuits or sheets etc., in water of the 
temperature for some minutes immediately after passing through the 
above rolling machine ; then re-rolling to the requisite thinness, and im- 
mersing again for a shorter time to ensure destruction of the enzyme. 
3rd. Hot water can be employed in the washing machine, and if 
necessary steam heated rollers as well. 
Heating while coagulating most nearly resembles the method of 
making hard para, but the other method gives excellent results. 
To insure the best product cleanliness in all stages of collection 
and manufacture is absolutely essential, and if the loss in value from 
want of simple precautions in the preparation was more fully realised 
on the estates, much greater care would be exercised. Many samples 
of excellent rubber appear on the London market, but from want of 
uniformity, and perhaps the presence of some slight impurity, they do 
not realise by some pence per lb., the value they otherwise would. 
Rubber made by this process, has already been sold on the market, 
and realised a premium of up to about 4d. per lb., over ordinary good 
biscuits which indicates that the process can be successfully applied on 
