CHAPTER XIII. 

 PHYSICAL AND CHEMICAL PROPERTIES OF RUBBER. 



Analyses of Para rubber from Ceylon, Bukit Rajah Co., F.M.S., 

 Penanu'. Straits, and Gold Coast — Market value of the samples — 

 Para and African rubber analyses compared — Resins in Para and 

 Castilloa rubber Resins in rubber from parts of the same tree — 

 Resins in rubber from Para trees of different ages— Para compared with 

 other rubbers — Chemical composition and value of Ceara. Castilloa. 

 Ficus, Landolphia, Crceola,and Rhynocodia rubber — Extraction of 

 resins from rubber by manufacturers and growers- Albuminoids and 

 .nuso of putrefaction — Removal by mechanicial and chemical pro- 

 cesses — Ash impurities and ingredients present in Para, Ceara. and 

 Alii can rubbers — The insoluble constituent in rubber — Properties of 

 indiarubber, reaction with alkalies, halogens, and acids — Absorption 

 of water-— Sulphur reaction — Action of heal on indiarubber. 



HAVING briefly indicated the composition and characters of the 

 latex as it appears in the factory of the cultivator, the same 

 features in the finished product can now be considered with a view 

 of gaining an insight into the changes which have taken place, and 

 the processes that have been adopted in Europe to free the rubber 

 of the impurities originally present in the latex. The prepared 

 article may be expected to contain all the insoluble components of 

 the latex, except those removed by mechanical operations. The 

 following analyses of plantation rubber, prepared from Hevea 

 brasiliensis in various parts of the world, may be taken as good 



* Tropical Agriculturist, Vol. XXIV. No. 5, November, 1904. 



t Journal d' Agriculture Tropicale, April. 1905. 



{Agr. Bull, of Straits and F.M.S., April, L904. 



§ Johnson ^Report on Rubber in the Gold, Coast, 1905, 



|| By M. Kelway Bamber, 



