88 



the standard of the market, but pound for pound of pure rubber is 

 really getting lower prices, for the Para rubber contains about 20 

 per cent, of moisture. Why this should be so is one of the great- 

 est problems before the investigator at the present moment. 



Any one comparing a sample of fine Para with one of any plan- 

 tation rubber — Ceylon, Malayan, or Mexico — can see at once 

 that the former is more springy, returning more readily to the ori- 

 ginal shape when stretched. The higher price really obtained 

 for this rubber may, therefore, probably be explained on this con- 

 sideration. 



Now, is it because the trees are young that the rubber is weaker, 

 or because the rubber is not smoke cured ? Is it because the rub- 

 ber is in biscuit or sheet instead of in blocks ? Is it that it is too 

 much dried (Para rubber contains 20 per cent, of moisture) ? Is it 

 that it is too pure and too much washed ? Or is it that it is not 

 coagulated in the best way ? All these, singly or in combination 

 are possible explanations, and there may be others. 



There is no doubt that older trees give stronger rubber, but that 

 of even the oldest trees in Ceylon — thirty years old — is not equal 

 to South American Rubber. Smoke-curing (without coagulation 

 at the same time) seems to strengthen the rubber, and block rub- 

 ber, besides a saving in cost of freight, and exposure of less sur- 

 face to oxidation, seems actually stronger than sheets or biscuits. 

 The great dryness of the plantation rubber may also have some- 

 thing to do with it, and experiments are now being tried by the Pe- 

 radeniya institution in the preparation of block from wet biscuits. 



To any one looking forward a little, one of the most interesting 

 exhibits in the show was the vulcanized and coloured rubber exhi- 

 bited by Mr. M. K. Bamber, Government Chemist in Ceylon. Mr. 

 Bamber acts, not on the coagulated and macerated rubber, but di- 

 rectly on the latex with the necessary reagents, and then coagu- 

 lates, giving a perfect intermixture. 



The coagulated rubber can then be worked up into whatever is 

 required in the ordinary way, and finally heated, when it vul- 

 canizes. One of the most promising of his exhibits was the mix- 

 ture of fibre and rubber. The fibre, cleaned, is soaked in sulphur- 

 ized rubber milk, coagulated and then dried, and finally subjected 

 to hydraulic pressure and vulcanized, the result being blocks 

 suitable for pavement, &c. By this method, rubber can also be 

 turned out of any colour desired, and the colour will not wash or 

 crack off— a great advantage for children's toys. One of the most 

 noteworthy features of the exhibition was a series of daily lectures 

 on the various parts of the rubber industry — cultivation, tapping, 

 shipment to London, vulcanization, catch crops, pests, &c, &c. ; 

 and these lectures with the reports of the judges, description of 

 the machinery and other things, are now being put together in a 

 book which will form a standard treatise,* to be in the hands of 

 every one interested in rubber. 



* The Ceylon Rubber Exhibition Handbook: by J. C. Willis, M. K. Bamber, and E. B. 

 Denham. To be obtained about the end of the year from Messrs Dulau & Co., 37 

 Soho Square, Messrs. Wyman & Sons, Ltd., Fetter Lane, London, for 7s. 6d. net. 



