Hums, Resins, 



444 



[Dec. 1906. 



must feel compelled to agree with that coiiclusion. Knowing how the plants have 

 flourished in the East, it is our next duty to enquire into the available details 

 regarding the commercial value of the produce, the methods of extraction, and the 

 yields obtainable. 



COMPARATIVE VALUE OF DIFFERENT RUBBERS. 



What do we know regarding the comparative commercial values of the 

 various kinks of rubber? It is true that most of the plantation rubber is valued at 

 the present time accordiug to appearance or physical properties ; though most of 

 the wild rubber is appraised by people who, from experience in the manufacture of 

 rubber goods in the factories, know the proportion of essential ingredients in the 

 raw rubber they handle. The home manufacturers are undoubtedly becoming aware 

 of the possibilities in plantation rubber, and though —often for very good reasons — 

 they have looked askance at several consignments, the day must come when from 

 constancy in chemical composition and physical properties, and from the constancy in 

 purity and output, the rubber from cultivated areas will receive their very serious 

 attention. During the last few years the output of wild rubber from several coun- 

 tries has been difficult to accurately forecast, and spec-ulation has naturally followed 

 such a condition of affairs ; the sources of plantation rubber on the other hand will 

 ultimately be well-known, and safer calculations of the probable output will be 

 possible. This constancy in output, and a guarantee of quality, grade, etc., possible 

 when dealing with well-managed plantations, will arrest attention in the near future. 



VALUE OF PLANTATION RUBBER. 



Though our plantation rubber, as at present prepared, may or may not have 

 the best physical properties, we are certain of one thing, and that is that we have 

 selected forms which in contradistinction to others may be described as pure types. 

 The three forms— Para, Castilloa and Ceara — yield rubber possessing a high percent- 

 age of caoutchouc, the component on which the real value largely depends, and on 

 account of which the synthetic chemists are working so perseveringly with hope of 

 success. Our Para rubber prepared even in the ordinary way possesses from 90 to 95 

 per cent of caoutchouc, and some samples of Ceara and Castiiloa rubber have from 

 76 to 90 per cent. Though many of the other rubbers may, when prepared by proper 

 methods, show a higher percentage of caoutchouc than they do at the present time, 

 it is doubtful whether they will ever exceed, by any appreciable amount, the 95 per 

 cent of caoutchouc which has been proved to occur in some samples from Bevea 

 brasiliensis and other species. Of course, there are other useful ingredients in rubber 

 and many believe that the proportion of caoutchouc can be reduced with advantage. 

 Undoubtedly the physical properties and the appearance of the plantation rubber 

 can and will be changed in course of time ; we kuow the nature of the processes by 

 which wild rubber is said to acquire some of the physical properties which manufac- 

 turers consider desirable. The production of rubber on the same principles as obtain 

 in the Brazilian forests is capable of being carried out in Ceylon, F.M.S., the Straits 

 and India not only as effectively, but at less expense, and the producer in the 

 tropics is only waiting for the unanimous order from the manufacturers to begin 

 work on those lines. 



We have been assured by Professor Dunstan, at the meeting of the British 

 Association just concluded at York, that the physical properties of raw rubber, on 

 which its technical value depends, are to be correlated with the chemical composition 

 of the material itself, and we are told that the elastic caoutchouc substance in each 

 of the finest rubbers is ot a similar nature. We already know that there are high 

 percentages of caoutchouc and favourable proportions of other ingredients in our 

 plantation rubber, satisfactory yields are obtainable, and most of the trees, 

 especially of Hevea brasiliensis, appear to stand tapping operations even when of a 

 very drastic nature. 



