RUBBER 371 



it has now been proved that true rubber can be made from the 

 hydrocarbon isoprene for which the formula CH 2 : C(CH 3 )-CH : 

 CH 2 was first proposed by Tilden, the question arises from what 

 sources such a hydrocarbon can be manufactured on a large 

 scale. It is scarcely necessary to point out that for the pro- 

 duction of rubber turpentine is out of the question, on account of 

 its cost and the comparatively small amount obtainable even 

 supposing the whole world produce were available. 



Since these investigations much research has been undertaken 

 on the problem. One result is that it is now recognised that 

 other hydrocarbons presenting the peculiarity of constitution 

 exhibited by isoprene, namely the presence of two double linkages 

 in the carbon chain, will also yield rubber-like substances. Another 

 wholly unexpected observation has been made by Dr. F. E. 

 Matthews. He found in 1910 that the hydrocarbon isoprene 

 in contact with a small quantity of metallic sodium is converted 

 in the course of a few hours or a few days, according to the 

 temperature, into a mass of pure rubber. The process was of 

 course patented. The same action of the metal was discovered 

 soon afterwards and independently by Professor Harries. The 

 great importance of this discovery of the sodium polymerisation 

 process lies in the fact that it is not seriously interfered with by 

 the presence of impurities, and that it does not require either a 

 high temperature or any considerable consumption of time. 



In what direction then are we to turn for a supply of a raw 

 material from which isoprene or some similar hydrocarbon can 

 be made ? The two requirements are that this raw material shall 

 be cheap and procurable in indefinitely large quantities. The 

 only substances fulfilling these conditions seem to be wood, 

 starch or sugar, petroleum, and coal. To describe even very 

 briefly the numerous attempts which have been made, in some 

 cases with considerable success, to produce rubber from com- 

 pounds originating in such materials would provide rather tedious 

 reading. It will be sufficient to indicate briefly the general 

 nature of the operations involved in two cases which appear 

 among the most promising. 



The first process is the subject of patents taken out by the 

 Badische Anilin und Soda Fabrik, the famous colour-makers at 

 Ludwigshafen. It starts with a fraction of petroleum spirit 

 which consists essentially of a mixture of pentanes C 5 H 12 . 

 These compounds are first exposed to the action of chlorine, and 



