336 



London, ijih, Februarv, igil. 



COPY. 



( From Imperial Institute, London, S. W. ) 



15th February, igil. 



Messrs Gow, Wilson and Stanton Ltd. 



13 Rood Lane, E. C. 



Dear Sirs, 



The three specimens of smoked rubber from the Botanic Gardens 

 at Singapore, which were forwarded with your letter o f the 2Ist 

 December, have now been examined with the following results: — 



No. I. A this sheet of dark brown rubber, slightly sticky on the 

 surface, and having a strong odour of creosote. The rubber was 

 fairly strong but appeared to be rather deficient in elasticity, as 

 strips when stretched elongated very considerably and showed little 

 power of recovery. 



The rubber had the following composition :— 





Rubber as received. 



Composition of dry 

 rubber. 





Per cent. 



Per cent. 



Moisture 



2.0 





Caoutchouc 



80.7 



82.3 



Resin 



5.5 



5.6 



Proteid 



4.1 



4.2 



Insoluble matter 



7.7 



7.9 





lOO.O 



lOO.O 



Ash 



1.0 



1.0 



The results of the analysis show that this specimen is abnormal 

 in containing a large proportion (7.7 per cent) of matter insoluble in 

 chloroform, and a very high percentage of ash. The insoluble por- 

 tion consisted ef dark brown flocculent matter which differed in 

 appearance from the so called " insoluble caoutchouc " frequently 

 present in Para Rubber. The amount of resin is very high for Para- 

 rubber and in this respect the sample resembles those previously 

 examined. The percentage of proteid is also high. 



No. 2. The sample consisted of pieces of light brown smoked 

 sheet and biscuit which were free from all traces of stickiness. The 

 rubber appeared to be a little stronger than No, I., but like the latter 

 was easily extended permanently on being stretched. 



The rubber had the following composition. 



Per cent. 



Moisture ... ... ... ... 0.5 



Caoutchouc ... •• ... ... 94-1* 



Resin ... ... ... ... 3.2 



Proteid ... ... ... ... 21 



Ash ... ... ... ... O.I 



* Including I.I% of insoluble caoutchouc." 



The percentage of resin, proteid and ash are all much lower in 

 this specimen than in No. I, and the amount insoluble in chloroform 

 is only 1. 1 per cent compared with 7.7 per cent in the preceding 

 sample. 



