RUBBERS AND GUMS 197 



quite widely. Recently the Russian Government has an- 

 nounced a process for the manufacture of artificial rubber 

 from vodka, and a similar process has been patented for 

 making rubber out of alcohol in the United States. The possi- 

 bility of producing artificial rubber on a real commercial basis 

 cannot be denied in toto, but synthetic rubber is still in an 

 experimental condition without commercial importance. As 

 has been well said, synthetic rubber is heard much more than 

 seen. 



Para rubber (Hevea brasUiensis) is a native of the Amazon 

 region and is now cultivated in Ceylon, Federated Malay 

 States, and various other places in the Tropics. This tree is 

 the source of the commercial Para rubber. In Ceylon and 

 the Federated Malay States there are now about 680,000 acres 

 of plantation Hevea from which the exportation of Para rub- 

 ber in 1913 was 12,300 tons. The Hevea tree is usually planted 

 at the rate of 100 to 150 per acre. It is customary to begin 

 tapping the trees at 5 years of age and the annual yield at this 

 age may be stated as about j/i pound per tree. At 10 years 

 of age the yield is 2 or 3 pounds, while at 15 years it reaches 

 4 to 6 pounds per tree per year. The Hevea tree reaches a 

 height of 100 feet when mature and a girth of 6 to 12 feet. 



The Ceylon light crepe rubber, obtained from plantation 

 Hevea, was once the world's standard for rubber. At present, 

 however, Upriver Para rubber from Brazil brings the highest 

 price. The wild trees in Brazil are tapped daily or every other 

 day or about 90 to 120 times during the dry season. The tap- 

 pers use a small ax with i-inch blade and attach a cup below 

 each incision. The latex is collected and taken to the huts 

 of the laborers, where it is coagulated in the hot smoke of 

 burning palm nuts into balls weighing 40 to 135 pounds. On 

 Hevea plantations, tapping begins when the trees have a girth 

 of 20 inches 3 feet from the ground. It has been found that 

 the flow of latex is most profuse in early morning. The most 

 widely used system of tapping is the half-herringbone method. 



