OUR FORESTS 



19 



use. The producís manufactured by forest industries have a yearly 

 valué of more than 3 billion dollars, not including paper and paper 

 producís, and in the valué of its producís íhe group ranks sixíh among 

 íhe leading indusíries of íhe Uniíed Síaíes. 



From íhe foresí also comes íhe raw maíerial used in íhe manufac- 

 íure of paper and numerous oíher producís. The basis of paper is 

 pulp made from fibers of cellulose, íhaí remarkable maíerial which 

 forms íhe framework and oíher construcíion maíerials of plañís. 

 Wood is íhe mosí abundaní source of cellulose in íhe plañí world, f or 

 more íhan one-half of iís subsíance is cellulose fiber. Wood pulp is 

 today íhe leading paper maíerial, alíhough paper has long been made 

 from unen and coi ton rags. 



Figure 12. — Lumber seasoning at the milis. 



Felled trees are cut into logs for transportation to the mili, where they are 

 trimmed and cut into boards. After the boards have been edged and trimmed, 

 they are sorted and sent to the lumber yard to be piled and seasoned. 



Four commercial processes of making paper from wood are in 

 general use: three chemical — íhe sulfiíe, sulfaíe, and soda processes; 

 and one mechanical — the ground-wood process. In each of the 

 chemical processes íhe chipped wood is cooked wiíh a chemical under 

 síeam pressure in a specially designed cooker, or digesíer. This 

 process removes íhe poríion of íhe wood known as lignin, which is 

 íhe maíerial íhat binds the cellulose fibers togeíher. In íhe ground- 

 wood process íhe uncooked wood is ground inío a pulp. Each 

 process is adapíed ío íhe manufacíure of ceríain grades of paper or 

 ío íhe pulping of ceríain woods, íhe síronger and beííer grades com- 

 ing from íhe íhree chemical processes. Among íhe woods suiíable 

 for pulping are spruce, hemlock, souíhern yellow pine, poplar, balsam 

 fir, jack pine, whiíe íir, beech, birch, maple, gum, and larch. 



The Uniíed Síaíes uses more paper íhan all íhe resí of íhe world. 

 In 1936 our consumpíion of paper producís amounted to no less 



