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values on chemical analysis should be instituted, but as this 
appeared to be unworkable it was abandoned. 
Manufacturers and buyers will always insist on basing their 
prices according to their own ideas of value arrived at by 
expert examination, and in this connection statements made 
recently by a chemist employed in one of the biggest rubber 
works in the world are appropriate—he gave it as his opinion 
that the best way of ascertaining the comparative values of 
different rubbers is by the trained eye. 
To sum up, I am convinced that the producer of cultivated 
rubber in the East possesses ali the conditions necessary to 
produce rubber more stable in quality than any other, provided 
his organization is perfected to such an extent as will ensure 
proper supervision being carried out in every department of 
collection and preparation. 
Dr. ScHiprowitz: Mr. President and Gentlemen—I think 
the first thing we must ask ourselves with regard to the 
question of variation, or variability, is: How do we define 
variability? It is quite true that wild rubbers vary, but the 
variation that exists in them is fairly obvious from their appear- 
ance; whereas plantation rubber is all of much the same 
appearance, and you may have grades which seem the same 
as regards colour, etc., but which in the process of manufacture 
turn out very differently. That, I think, is the specific differ- 
ence between the variation of plantation rubber and of wild 
rubber. 
We have had some very interesting evidence from Mr. 
Williams regarding the nature of the variation in the factory, 
and I am glad to see that he confirms the view which I ex- 
pressed some time ago—a view, I may say, which was based 
on a great deal of experimental evidence—that the most 
important factor in regard to variation of the product is its 
rate of cure. Now in some particulars I agree with Mr. 
Williams, and in others I dissent from him, and I would ask 
you not to regard it as entirely presumptuous on my part to 
differ from an eminent manufacturing expert, because we who 
are not actually engaged in factories get into more factories, 
and see more of the general operations in various factories 
than a specialist who is attached to one individual factory. It 
is my experience, and I am sure it is the experience of every 
technologist, that one manufacturer will say that a thing is 
black, while the next manufacturer will say that the same thing 
is white; and yet we poor scientists, or technologists, or what- 
ever you like to call us, are told that we know nothing of 
the practical aspect of affairs, though when we go into the 
factories of practical men we hear opinions expressed which are 
diametrically in opposition to one another. 
