WOOD AND ITS USES 317 



the northwest, Douglas fir, western larch, ponderosa and lodge- 

 pole pines are used. 



The lengths and other specifications for mine timbers vary 

 with local conditions and requirements. The production of such 

 timbers is usually a separate business, though closely associated 

 with small sawmill operations in the mining districts, where it 

 results in more complete utilization of the tree, since pieces as 

 small as two inches in diameter are used. Unfortunately, farm 

 woodlands sometimes have their young, rapidly-growing stands 

 of trees clear cut for mine timbers. Because of the warm, damp 

 atmosphere of most mines, wood decay is very rapid in untreated 

 timbers. Consequently preservative treated timbers are widely 

 used in the more permanent parts of the mine, with untreated 

 woods used in the temporary branches and tunnels. 



2. Chemical Derivatives 



Wood consists of a groundwork of cellulose, an organic chem- 

 ical substance which is readily converted into sugars. This 

 cellulose is cemented together in the form of cells by lignin and 

 infiltrated with gums, tannins and resins. These must be removed 

 from wood pulp before rayon, cellophane, white paper or many 

 other cellulose products can be manufactured. 



Chemical derivatives of wood have increased greatly in 

 importance among forest industries as more has been learned 

 concerning the chemistry of the basic substances composing 

 the wood. They are due to become increasingly important as 

 more knowledge is gained and as complete utilization of wood 

 becomes more imperative. 



Wood pulp and products manufactured from it. — The 

 pulp and paper industry is one of the ten largest industries in 

 the United States, 4% of the total timber cut being pulp wood. 

 In Eastern Canada it is the most important single industry. 

 Paper manufactured entirely or in part from wood pulp con- 

 stitutes 90 % of all American made paper. The wood pulp indus- 

 try is in a constant state of change, due to the large amount of 

 successful research being conducted to determine methods and 

 species adapted to pulping. Early in the development of the pulp 



