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in working of the two classes of rubber, and in several cases — 
notably at Silvertown, where accurate tests of all rubbers used are 
carried out, the recorded figures were submitted to my inspection, 
and an inferiority of from 8 per cent, to 15 per cent, with different 
samples was shown. The inferiority of plantation rubber is not 
only confined to those physical properties which are capable of 
immediate measurement, but is also shown in the keeping qualities 
of the rubber. I was shown samples from different estates in 
Ceylon and the Straits which had been sent home in 1902 and 1903, 
and which had been preserved in air-tight jars side by side and in 
the same room with samples of jungle rubbers from South America 
and Africa. One sample prepared in 1902 was quite perished and 
rotten, its elasticity w r as entirely lost, and it was more like a sheet 
of dough*than rubber. Other samples of plantation rubber had all 
shown marked deterioration in the three years. To compare with 
these were samples of South American Para of ages up to and over 
forty years which had preserved perfectly their tough and elastic 
qualities. This feature of plantation rubber is one which is now 
beginning to be realised, and though it probably is due to errors 
committed in preparation of the samples in question two or three 
years ago, it confirms practical users of rubber in their opinion that- 
plantation rubber is not reliable, and certainly not the equal of 
South American Para. 
13. The cause of the inferiority of plantation rubber when com- 
pared with pure South American Para rubber is not known. Some 
of the manufacturers believe it to be due to differences in the 
locality, climate, and conditions under which the trees are grown ; 
others incline to the belief that, the difference in quality is the 
result of difference in mode of-curing and exporting, and again the 
difference in age of tree from which the rubber is gathered may 
very probably be the actual reason for the difference in quality of 
the rubber. There is a further suggestion which has, I believe, 
never yet been made. The rubber trees of South America which 
are tapped are selected both by natural and by artificial selection. 
The condition in South America is, I understand, one of jungle in 
which the trees affect, and compete with, one another, and this 
leads to the survival, by natural selection, of the finest and most 
sturdy only of the seedlings. The native in tapping selects the 
best of the trees he conveniently can, and here the influence at 
work is one leading to the rejection of weak and badly developed 
trees. On the plantation after the first selection of the stumps 
and seedlings, no further selective process is actively at work. To 
determine whether this has any influence on the quality of the 
rubber, tapping should be done on specially selected trees, and the 
quality of the rubber extracted compared with the average rubber 
of that plot of trees. All opinions at present must be looked upon 
as guesses at the solution of this question, the only thing certain is 
that plantation rubber is inferior, and this certain knowledge is one 
of the most important results of my visit to England. I propose 
to endeavour to find out in Singapore, and on the plantations 
themselves, the actual reasons of this inferiority by experimental 
