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Mr. W. A. Wituiams (North British Rubber Company): 
Mr. President and Gentlemen—The question before us has 
been divided into three headings, and I should like to say a 
few words about division No. 1, and also to make some 
reference to our experience as regards No. 2. 
In the first place as to the variation itself, and how it affects 
the manufacturer. Our chief trouble in the factory in handling 
this grade of rubber is due to the great changes which we 
have to make in connection with our organization, especially 
in respect to vulcanization adjustments. We find that the 
variations in the heat which we have to give the compounds 
range over a pretty wide figure. I say this not as dealing with 
any small quantities of rubber, for I may mention that we are 
using in our factory a very large quantity, and 80 per cent. 
of our total consumption is plantation rubber. But at the 
same time we can only use this plantation rubber with a con- 
siderable amount of control and careful watching. I will just 
give you three examples, in order to convey to you some idea 
of what we have to contend with. The first one is a case 
where we were manufacturing moulded goods, and the heat 
varied from 60 minutes at 50 lb. to 70 minutes at 50 lb.—a vari- 
ation of 16°6 per cent. The next case was one of open steam 
cure, where the variation was from 2$ hours at 270° F. to 
34 hours at 270° F.—a variation of 4o per cent. In the third 
case, which took place only within the last fortnight, where 
we were dealing with wrapped goods, open heated, the heat 
had to be changed from 40 minutes at 50 Ib. to 80 minutes at 
52 lb.—a variation of over 100 per cent. I think these instances 
will show you that there is considerable variation to deal with. 
The next question which appeals to us, and on which we 
have done a considerable amount of work, is as to why this 
variation takes place. Although this question is more in the 
hands of the chemists, I think I may be excused for speaking 
a little on it, as I myself was Chief Chemist to the North 
British Rubber Company for some considerable time. I think 
the first thing which occurs to anyone who has experience in 
dealing with rubber, is that plantations are in the habit, with 
certain grades, of giving the rubber a considerable amount of 
working before it is put on the market. I refer particularly to 
créped and block rubbers. As a matter of fact, we have now 
discontinued using these classes of rubbers, and we only use 
unsmoked biscuits or sheet. We find that the unsmoked 
biscuits or sheet give just as good results as the smoked, and 
infinitely better than the créped and the block. It is rather 
hard to understand why the plantations should crépe their 
rubber. It is a rudimentary principle of the rubber manu- 
facturer that the more you work your rubbers the more you are 
