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Mr. W. A. WILLIAMS (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. i, 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 Ib. to 70 minutes at 50 Ib. a vari- 

 ation of 16*6 per cent. The next case was one of open steam 

 cure, where the variation was from 2j hours at 270 F. to 

 3 1 hours at 270 F. a variation of 40 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 minute's at 

 52 Ib. 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 

 creped 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 creped and the block. It is rather 

 hard to understand why the plantations should crepe their 

 rubber. It is a rudimentary principle of the rubber manu- 

 facturer that the more you work your rubbers the more you are 



