135 
impossible to handle the rubber, and we found that 3 per cent. 
was the maximum figure. At about that figure vulcanization 
became impossible. 
I do not think there is anything more which I can add at the 
moment to the discussion, except to bring forward these 
examples of variations which materially affect our working of 
plantation rubber. 
The Presipent: I think we shall all be agreed that Mr. 
Williams has given us a very interesting contribution. May 
I ask whether any other gentleman would wish to speak from 
the user’s or manufacturer’s point of view? (There was no 
response.) Then we will pass to the second division of the 
subject. 
Mr. Spencer Brett (Messrs. Gow, Wilson and Stanton): 
Mr. President and Gentlemen—This is a subject which has so 
exercised the minds of scientists that in approaching it I must 
disclaim all intention of treating it from a strictly scientific 
standpoint, and in touching upon the various problems involved 
I wish it to be clearly understood that I hope to offer sugges- 
tions only, and that I do not presume to be able greatly to 
enlighten either the chemist or the planter. 
At the outset the very statement that plantation rubber shows 
excessive variation seems open to argument. It must be 
admitted that Eastern cultivated rubber has, especially in its 
earlier years, had to withstand an exceptionally severe ordeal. 
When the produce of a few isolated trees first reached the 
market it was examined side by side with a commodity which 
had been an established commercial proposition for very many 
years. 
Generally speaking, by the time wild rubber reaches the 
consumers’ works it has gone through a variety of bulking, 
sorting and grading processes, both natural and artificial, 
and it is evident that in the early plantation days the conditions 
were most unequal for comparison. 
Dealing with the present, we are faced with the fact that 
the quality of plantation rubber does show variation, and in 
the interests of the industry every step must be taken to 
standardize the quality to the utmost extent. 
It is now generally known that much of the variation is 
attributable to differences in any or all of the many details 
of preparation. It is necessary, however, to go further back 
than this. A natural variation must exist in the richness and 
character of the latex as collected from the trees; this again 
is not only dependent on climatic conditions, but may be 
directly influenced by the frequency of tapping, elevation or 
character of lands, length of time during which trees are 
rested, age of trees, distance of planting and many other 
considerations. 
