20 PARA RUBBER. 



ARTIFICIAL OR SYNTHETIC RUBBER. 



The possible profitable production of synthetic rubber has 

 now been an incubus to the rubber producer for over sixty years, 

 and appears to be as far off materialisation as ever it was. The 

 records at the Patent Office show that more than three hundred 

 inventions of rubber substitutes have been filed. Tilden's 

 reported manufacture of synthetic rubber in 1882 from isoprene 

 has since been questioned by Harries, who has shown that the 

 constitution of rubber renders its manufacture from isoprene 

 improbable. Isoprene may be separated from the oil of turpen- 

 tine and also from colza, castor, and linseed oils. Isoprene is 

 colourless, but if it be exposed to the light for several months its 

 consistency changes to a syrupy nature in which yellow matter 

 resembling rubber may be observed. This has been determined 

 by certain scientists to be synthetic rubber. Rubber substitutes 

 have for years been manufactured from the seeds of poppy, rape, 

 castor, and flax, for the express purpose of mixing with crude 

 rubber in the manufacture of various rubber goods, and new 

 substances suitable for that purpose are being constantly 

 discovered. These form the bases of the majority of the so- 

 called synthetic rubber discoveries, but which are in reality 

 rubber substitutes mixed with crude rubber. 



Rubber consists of very complicated compounds of proteins, 

 resins, and caoutchouc, the exact chemical composition of which 

 is not yet thoroughly understood by chemists ; it is consequently 

 improbable that synthetic rubber will be commercially manufac- 

 tured until these problems have been more satisfactorily solved. 

 Chemists who have devoted considerable attention to the study 

 of rubber still speak dubiously of the probability of the profit- 

 able manufacture of synthetic rubber on a large commercial 

 scale. 



Synthetic rubber, to compete favourably with Para rubber, 

 must possess not only all its chemical constituents but, in 

 addition, all the valuable physical properties for which Para 

 rubber is so much esteemed. 



