426 ELEMENTARY STUDIES IN BOTANY 



is introduced in the southern pineries, the resin industry is 

 doomed to destruction. 



The bark of certain trees is also used as a source of tannic 

 acid for tanning leather. In Europe, oaks are extensively 

 propagated for this purpose, but in the United States hem- 

 lock bark is used. With our usual recklessness the trees 

 are practically destroyed in securing the bark, so that now a 

 large amount of our tannin comes from South American 

 woods. 



The destructive distillation of woods yields a remarkable 

 variety of products that need not be enumerated, chief 

 among which are wood alcohol and tar (from the distillation 

 of pine). In every case, after the desired product has been 

 driven off by distillation, charcoal is left. 



Any consideration of the products of trees must include 

 maple sugar and syrup. This is said to be the only forest 

 industry that has been developed on a scientific basis. It is 

 an American industry, and when it is known that over 

 50,000,000 pounds of sugar and 3,000,000 gallons of syrup 

 are produced each year, it can be appreciated that the indus- 

 try is a large one. Vermont is the leading state in maple 

 sugar production, producing 15,000,000 pounds of sugar and 

 100,000 gallons of syrup in a year. 



In this connection mention may be made of the common 

 sources of commercial sugar. Sugar-cane (a grass) has 

 been used longest as a source of sugar, and in this country 

 the industry has been most developed in Louisiana. The 

 manufacture of sugar from beets is a much newer industry, 

 and has developed on a large scale in the United States. In 

 the production of sugar from sugar-cane, India leads the 

 other countries, followed by Cuba, Java, and the United 

 States. The world's production of sugar from cane in 1903 

 is estimated to have been about 4,000,000 tons ; and of sugar 

 from beets about 5,800,000 tons, 5,600,000 tons of which was 

 produced in Europe. In 1911 the production of sugar from 



