542 SCIENCE PROGRESS 



rubber planter. He needs the aid of specialists in entomology 

 and mycology almost every month to attack the diseases that 

 threaten his trees, and of the chemist for their scientific 

 manuring ; but there are also many directions in which new 

 discoveries have to be made before we can look upon the rubber 

 industry as beyond the fear of competition from the wild 

 materials collected in South America, Africa, etc. Thus we 

 want to find out, as soon as may be, why the cultivated rubber 

 is less elastic than the wild South American ; it does not 

 immediately go back to its original form on being stretched. 

 We want to find out the very best way of tapping to get the 

 maximum yield with the smallest consumption of bark. We 

 want to find out how best to coagulate rubber into marketable 

 form, and many other things. 



To those who look forward more than a few months, one of 

 the most interesting exhibits in the whole show was the samples 

 of coloured and sulphurised rubbers exhibited by Mr. Kelway 

 Bamber, Government chemist in Ceylon. At present the 

 colouring, vulcanising, and mixing reagents are added to the 

 rubber after coagulation. The raw rubber is macerated in 

 powerful engines, and thoroughly mixed with the various 

 substances, and then worked up into the finished articles, and 

 heated at the end, when vulcanisation takes place. It seems 

 waste of time, energy, and money to do this mixing in the dry 

 rubber, when it can be much more easily and cheaply done in 

 the milk. The milk is filtered, in the Bamber process, and then 

 mixed with the vulcanising and colouring agents, which, of 

 course, become absolutely intermixed with a little stirring. 

 The vulcanising agents used are such as give free milk of 

 sulphur on the addition of an acid, and acid is added to the 

 mixture to such an extent as to free the sulphur and coagulate 

 the rubber, which is thus formed with sulphur in contact 

 with almost every molecule. This rubber can then be treated 

 in the ordinary way, and made up into rubber goods, 

 which, when heated at the finish, vulcanise. In the same way 

 colours, fibres, mixing substances of every description (pro- 

 vided that they can be wetted) can be added to the milk, 

 and mix homogeneously with it. While requiring as yet 

 much elaboration in detail, this method holds the germs of 

 the future treatment of rubber, and there is probably a great 

 future before it. 



