198 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1940 



TLANTATION RUBBER 



In 1876 an event occurred which was destined to create a profound 

 change in the production of rubber. An Englishman, Henry Wick- 

 ham, succeeded in transporting a supply of seeds of the Hevea tree 

 from Brazil to England. Wickham had previously devoted several 

 years to the study of these trees in their native jungles, and had se- 

 lected and carefully picked seeds from the best type of tree. The seeds 

 were planted in Kew Gardens, and the seedlings from them were 

 transplanted in Cejdon. 



In spite of what appeared to be a good start, plantation rubber 

 developed slowly. In 1909, 3,600 tons of plantation rubber and 

 66,000 tons of wild rubber were produced. By 1913-14 the produc- 

 tion of plantation rubber equaled that of wild rubber. At present 

 practically all the world's supply of rubber comes from the planta- 

 tions, and the total potential world production has grown to around 

 1,500,000 tons per year. 



Great improvements have been made in the art of growing rubber. 

 The early books on the plantation industry record yields of around 

 300 pounds per acre. A great deal of work was carried out in the 

 East on the application of genetics to rubber planting; as a result 

 the yield has been greatly increased. At present the average annual 

 yield per acre on the European and American owned plantations is 

 450 pounds per year. High yielding areas have produced as much as 

 2,000 pounds per year. 



Although the trees planted in the East are of Brazilian origin, 

 the type of crude rubber produced on the eastern estates is quite 

 different from the Para rubber of Brazil. The plantation rubber 

 in practically all cases is made by coagulating latex by the addition 

 of an acid, such as acetic or formic, and then forming the coagulum 

 into a sheet which is washed and dried. In many cases the sheets 

 are hung in a smokehouse, and the product is known as smoked 

 sheet. 



INVENTION OF THE PNEUMATIC TIRE 



Another event of far-reaching importance was the invention of 

 the pneumatic tire, patented by Dunlop in 1888. Dunlop's first tire 

 was a rubber tube, with means for inflation, held to the rims of a 

 tricycle by tape. The introduction of the bicycle gave an impetus 

 to the development of tires, which was still further stimulated by 

 the invention of the automobile. 



SCIENTIFIC WORK TO 1890 



Let us now consider the scientific work which was done between 

 1839 and 1890. Goodyear's discovery was made at a time when 

 chemistry was in its infancy. Although a few of the basic chemical 



