CHAPTER XIX 

 RUBBER 



GENERAL 



Rubber — also commonly called india rubber and caoutchouc in the 

 trade — is the product of the milky juice or latex found in a variety of 

 trees, vines and shrubs of the tropics. The true function of latex in 

 the life and development of the tree has not been fully determined as 

 yet. It is found secreted in the vessels and small sacs in the cortical 

 tissue between the outer bark and the wood. It also occurs in the leaves, 

 roots and other parts of certain tropical plants. 



The latex is derived from the bark by making an incision at regular 

 intervals through the outer layers of bark. This milky fluid contains 

 from 20 to 50 per cent of crude rubber. 



Rubber is one of the most important forest products used by man- 

 kind. The value of rubber imported to this country is more than twice 

 the total value of all other forest products brought to this country from 

 foreign sources, including lumber, tanning materials, dyewoods and 

 materials, pulpwood, wood pulp, etc. In 191 7 the value of rubber 

 imported to this country was $233,220,904. 



The rubber industry has made greater advances, measured both in 

 the quantity and value of its product, than any other forest industry 

 in the world. The demands of the automobile industry for rubber tires 

 have been enormous, and the production of crude rubber has been equal 

 to the demand. Little rubber of any kind was used fifty years ago and 

 the process of making crude rubber available for modern arts and indus- 

 tries was only discovered less than one hundred years ago. 



In the year 1900 the total world's production of rubber was only 

 120,713,6001b.; in 1910 the total output was 157,920,000 lb., but in 1915 

 the production rose rapidly with the increased demands for rubber tires 

 for automobiles, and in that year the output was 355,492,480 lb. More- 

 over, the demand was not satisfied even with that enormous yield and in 

 1918 the world's production had risen to the enormous total of about 

 600,000,000 lb. 



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