Oct. 1906:] 



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Saps and Exudations. 



The drying room should have a free circulation of air, and the darker it is 

 maintained, the more valuable is the resultant dried rubber. The rubber is then 

 stored until required for industrial purposes. 



THE MASTICATION PROCESS, 



The loss in weight in washing and drying of raw rubber is very variable, 

 sometimes rising as high as 00 per cent in inferior kinds, while hard Para loses 10 

 to 16 per cent, and plantation Para only 1 to 4 per cent. When required for manu- 

 facture, the rubber has to undergo a further process of mastication or kneading 

 by frequent passing between massive, hollow steam-heated rollers over 1 feet long 

 and 19 inches in diameter. One roll is usually smooth, the other grooved, and they 

 revolve at unequal speed, the latter twice as rapidly as the former. The distance 

 apart is capable of regulation, and the rubber is forced through again and again 

 until it becomes perfectly homogeneous in character. Great care is necessary in 

 the process, which, if the rubber is not perfectly dry, takes from 40 to 50 minutes, 

 according to the amount of moisture that has to be evaporated. In most factories, 

 rubbers from different sources are masticated separately — some African varieties, 

 which become tacky under the action of the hot rolls, taking a much longer time, 

 and their sticky character necessitating the addition of a little talc (hydrous silicate 

 of magnesia). 



THE VULCANISER. 



I would here like to briefly describe the form of vulcaniser. This is a small 

 vertical boiler with a small copper cylinder into which the objects you wish to 

 vulcanise would be placed. Water is placed in the cylinder and the whole 

 apparatus is closed and heated until the steam pressure reaches 3 to 4 atmospheres. 

 With a low proportion of sulphur in the rubber, vulcanisation can take place in 

 about half-an-hour. With a high proportion you want 3 to 4 hours to vulcanise. 

 The actual time required for vulcanisation is one of the most important points, 

 and it is very easy to spoil a whole batch of goods by a half, or even a quarter of 

 an hours over- vulcanisation, so that when you have perhaps a ton or more of manu- 

 factured articles in these large cylinders being subjected to the vulcanisation 

 process, it requires a large amount of experience to know exactly when the articles 

 are likely to be over-vulcanised ; otherwise a little over-heating might spoil 

 them entirely. You have all seen in the Exhibition the various kinds of rubber 

 which have to be vulcanised, including large blocks which have to be torn and 

 macerated and mixed with sulphur or other powders until the mixture becomes 

 perfectly homogenous— that is to say, that if you cut a section and put it under the 

 microscope the whole section is perfectly uniform. From the description I have 

 given, you can see an enormous amount of time and power is employed in this 

 process. 



TO SULPHURISE RUBBER IN CEYLON. 



What we propose to do out here is to save that time and power by adding 

 sulphur or sulphur compounds to the latex direct from the tree. I have here a 

 sample of latex. I do not know the exact proportion of rubber in this latex, but it 

 is very easy to ascertain the amount. You then would add a measured quantity of 

 this sulphur solution, of which you kuow the exact proportion of sulphur, and you 

 will see that it is capable of instantaneously mixing with the latex, so that a per- 

 fectly intimate mixture is obtainable. This would be done in huge vats, and it 

 would mean that the latex from various estates could be amalgamated and a very 

 uniform product obtained. By a slight stirring you get a perfect admixture. On 

 the addition of the acid to this rubber— in the usual way you coagidate rubber in 

 Ceylon— the sulphur would be thrown out of solution, but as the sulphur is in an 

 extremely fine state of division, you will find no sedimentation and it is thrown out 



