June, 1910.] 



485 



Saps and Exudations, 



and the advantage of lower cost would 

 thus tend to disappear,' 



Coming now to true synthetic rubber ; 

 a question often asked is whether there 

 exists any probability of such an article 

 being manufactured and displacing 

 natural rubber, either wholly or to any 

 large extent. Will rubber plantations 

 go the way of madder fields and indigo 

 cultivation ? Well, the future is on the 

 knees of the gods. In the face of the 

 precedents just mentioned, to say 

 nothing of others, he would be a bold 

 man who would venture to say that 

 even the best quality of rubber may not 

 some day be made on a commercial scale 

 from cheaper materials such as beet 

 sugar and calcium carbide. But the day 

 is not yet. There are beginnings ; there 

 are clear indications of the direction in 

 which to proceed ; there is distinct pro- 

 gress to note. But there is still some 

 distance to go, and the eud of the 

 journey may not be even in sight, 



India rubber chemically is essentially 

 a polymerised terpene. An article 

 patented some time ago, and named 

 " turpentine rubber," appears to fore- 

 shadow a synthesis of true rubber. 

 Turpentine is a mixture of terpenes, and 

 the article in question was to be ob- 

 tained by passing turpentine through a 

 hot tube, and treating the resulting 

 vapours with hydrochloric acid: The 

 result is a solid condensation-product ; 

 and the idea at the base of the process 

 appears to be the production of poly- 

 merised terpenes having some of the 

 elastic properties of rubber. 



A more promising, because a more 

 scientific way, is that outlined in Heine- 

 mann's patent No. 21,772 of 1907. Here a 

 true synthesis is attempted. It is based 

 upon the well-known fact that rubber is 

 probably a polymer of the semi-terpene 

 isoprene. The first step is the produc- 

 tion of the unsaturated hydrocarbon 

 divinyl, CH2: CH, OH: CH 2 . This is 

 obtained by passing mixed acetylene 

 and ethylene gases through a heated 

 tube. With methyl chloride, divinyl 

 yields isoprene (methyl divinyl CHs: 

 C (CHs). CH : CH2) ; and the isoprene on 

 treatment with strong hydrochloric acid 

 is converted by a union of molecules into 

 a substance closely resembling caout- 

 chouc, if not identical with it. The raw 

 materials, so to speak, are thus acetylene, 

 ethylene, and methyl chloride, which are 

 themselves obtained by any of the ordin- 

 ary methods, e.g., from calcium carbide, 

 alcohol, and beet sugar residues respec- 

 tively. The question is, can this or 

 some other comparatively simple syn- 

 thesis, theoretically quite possible as a 

 laboratory operation be translated into 



a practicable and profitable mode of 

 manufacture on a large scale ? One of 

 the first doubts to arise is whether the 

 synthesised caoutchouc will have the 

 physical properties of natural rubber ; 

 or whether these, by any course of treat- 

 ment can be imparted to it. This doubt 

 resolved, there comes the question of 

 economical production in competition 

 with the natural product. Much time 

 and thought have been spent on the 

 problem of synthetic rubber, and it is 

 safe to conclude that there will yet be 

 many a headache before it is solved. 

 Judging by what is known to have been 

 done rather than by the promises, 

 owners of rubber plantations may for 

 the present? sleep peacefully in their 

 beds. 



DANGERS, MISTAKES, AND 

 IMPROVEMENTS IN THE CAOUT- 

 CHOUC PRODUCTION OF ASIA. II. 



(By D. Sandmann in Tropenflanzer, 

 April, 1910. Abstracted by J. C. Willis.) 



The milk should as soon as possible 

 be made into rubber, before decompo- 

 sition sets in. He states that rubber 

 made by allowing the milk to stand un- 

 til sour is less elastic. The milk in 

 transport to the factory should be pro- 

 tected from the heat of the sun. He 

 recommends a horsehair sieve as more 

 easily kept clean. 



The various methods of coagulation, 

 and machines in use for preparation of 

 rubber are then described. 



PUNTUMIA ON THE IVORY COAST. 



(By A, Chevalier, Journ, d'Agri. trop., 

 February, 1910. Abstracted by 

 J. C. Willis.) 



M. Chevalier leaves undecided the 

 question whether Funtumia or Hevea is 

 best suited to Western Africa. The 

 former is of course native there, whereas 

 here in the East, where both species are 

 foreign, Funtumia has shown itself very 

 liable to the attack of a native cater- 

 pillar, and its cultivation involves a 

 good deal of expense in spraying, and 

 its growth is but slow. 



Rubber can be prepared by boiling the 

 latex, and this method is recommended 

 for native use, though the natives are 

 giving it up in favour of coagulating by 

 aid of the latex of certain lianes, such as 

 species of Strophanthus ? or sometimes 

 by solution of soap (h a bar of Marseilles 

 soap to 45 litres of latex). 



