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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 créped 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 
unsmoked, 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 1 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 per cent., and that the time of vulcanization was increased 
to the extent of 18 per cent. by one-eighth of 1 per cent. of 
bisulphite, while a quarter of 1 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 
