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going to lose in respect to " nerve " and strength, and I think 

 that any grinding the rubber has to undergo should be left to 

 the manufacturer himself to do, so that he may himself give 

 it the correct condition for putting in his compounds. This 

 grinding, I believe, in many cases is done by machines which 

 even the manufacturer would not use in his factory. They 

 have too high a friction between the rollers, which causes 

 considerable grinding, loss of " nerve," and wear on the 

 rubber, and in some cases this grinding might be carried to 

 such an extent (which is not an unknown thing even in a 

 factory if inexperienced workmen are employed) that vul- 

 canization becomes impossible. Take the finest Para rubber : 

 you may give it such working that you cannot vulcanize it 

 afterwards ; and more or less that is what is taking place with 

 the creped rubbers, and the same, of course, applies to block 

 rubbers. Our reason for not using the smoked rubber is that 

 as regards strength we get no better results. We have a 

 slightly higher washing loss on smoked than we do on 

 tinsmoked, and we have a slightly higher resin content. The 

 washing loss is, of course, purely a commercial question, but 

 the high resin content is against the use of smoked rubber for 

 the manufacture of goods against a chemical specification, 

 which is very largely coming into use nowadays; in such cases 

 we find that we are handicapped in having a higher resin 

 content in the rubber. 



There is just one other point I would like to mention, and 

 that is in connection with pale rubbers. It has become a 

 practice, and rather a large one, for pale rubbers to be put 

 on the market, and sodium bisulphite is used on the plantations 

 for getting this pale result. As manufacturers we are not 

 interested at all in a pale rubber, and our experience is that 

 the dark rubbers give better results than the light ones. We 

 are now carrying out some experiments in connection with 

 this question of the use of sodium bisulphite. We took some 

 rubber free entirely from sulphur, and we incorporated with 

 this rubber varying percentages of bisulphite, working up to a 

 quarter of I per cent., which we found corresponded to a good 

 deal of the rubber delivered to our factory, and in some cases 

 I may say we get up to half of i per cent, of bisulphite. We 

 found, on the average results of the experiments, that a quarter 

 of i per cent, reduced the stress by 20 per cent., and the strain 

 by 15 percent., and that the time of vulcanization was increased 

 to the extent of 18 per cent, by one-eighth of i per cent, of 

 bisulphite, while a quarter of i per cent, of bisulphite increased 

 the time of cure 27 per cent. We carried the experiments a 

 little further in order to find what was the total quantity of 

 bisulphite which would so affect the cure that we should find it 



