RUBBERS AND GUMS 203 



after a slight injury of the bark and coagulates within a short 

 time after exposure to the air has been cited as showing how 

 effectively the latex protects the tree against wounds. As al- 

 ready indicated, latex commonly contains from 55 to 70 per 

 cent, of water and a varying percentage of resin which de- 

 creases with the age of the tree in all commercial rubber plants 

 except Hevea, in which even in young trees the latex contains 

 only about 2.^/2. per cent, of resin. 



From many related plants the abundant latex is so low in 

 caoutchouc and so high in resin that the dried product is used 

 for other purposes than rubber. Some of the most important 

 cases in point are chicle, balata, gutta-percha, and jelutong, 

 which are discussed below. 



At the present time the areas planted in rubber are in Ma- 

 laya 625,000 acres, in Java 230,000 acres, in Sumatra 160,000 

 acres, in Burma 40,000 acres, in Borneo 25,000 acres, in East 

 Africa 60,000 acres, in Kamerun 17,000 acres, and smaller 

 areas in plantations in various other tropical countries. It is 

 estimated that the total area of plantation rubber by the close 

 of 1916 will represent 1,500,000 acres, and the estimated out- 

 put of plantation rubber in 1920 will be 200,000 tons. Ac- 

 cording to the latest available statistics, the annual production 

 of wild rubber from Brazil is 45,000 tons, from Africa 21,000 

 tons, from Mexico 8,000 tons, from Bolivia 3,000 tons, and 

 from Peru 2,000 tons. 



The enthusiastic stampede which characterized the develop- 

 ment of the rubber industry during the past twenty years led 

 to the organization of many doubtful rubber companies, the 

 perpetration of a great many hoaxes in the sale of rubber 

 plantations, and the sale of much worthless rubber stock. Not- 

 withstanding these unfortunate experiences, it is the best judg- 

 ment of men most familiar with the rubber industry that 

 when rubber finally reaches the stable price of 50 to 60 cents 

 per pound, or perhaps somewhat lower, its use will doubtless 

 be greatly extended beyond even its present development, and 



