WOOD PULP AND PAPER 23 



fiber. Woods in which these characters stand out make the best paper 

 and are used with comparative economy. 



2. The wood should be relatively free from intercellular constituents, 

 such as resins, gums, tannins, etc. Highly resinous woods and those 

 containing large percentages of tannins, gums, etc., are converted into 

 paper with considerable difficulty and are used only for the cheaper 

 grades of paper. 



3. The wood must be available in sufficient quantities, reasonably 

 accessible and, therefore, fairly economical in price. Some woods are 

 admirably adapted to the manufacture of pulp and paper, but are often 

 eliminated because they are not sufficiently available or are in greater 

 demand for other purposes. 



4. White fibered woods are preferred since most papers are white or 

 light in color. Bleaching at great expense is required to whiten some 

 woods. Woods which are white or nearly so are much more in demand 

 than those of deep or dark colors. 



5. The wood must be sound, reasonably clear of knots, free from rot, 

 dote, bark, pitch pockets, and other defects. Sound wood, clear of all 

 foreign matter or defects is especially required in certain processes of pulp 

 manufacture. 



6. The wood itself should contain large quantities of available cellu- 

 lose. Most woods contain between 40 per cent and 60 per cent of cel- 

 lulose. Since the basis of all paper is cellulose, it is desirable to select a 

 wood for pulp that contains cellulose in a form that is readily separated 

 without loss by the destructive action of chemicals which are used in 

 cooking processes. 



ANNUAL CONSUMPTION OF WOOD 



At the present time it is estimated that about 6,000,000 cords of wood 

 are now annually used in this country for wood pulp. The latest avail- 

 able accurate figures are those published by the United States Forest 

 Service for the year 1916, when it was reported that 5,228,558 cords of 

 wood were manufactured into pulp at 230 mills. Of this amount Canada 

 supplied about 700,000 cords, or 15 per cent of the total quantity. 

 There has been a steady increase from year to year in the consumption of 

 wood. 



While the number of mills has not increased Iso rapidly from year to 

 year there has been a strong tendency to increase the size of our American 

 pulp mills. The average number of cords used annually in each pulp 

 mill in 1911 was 16,149 and in 1916 was 22,735. Some mills consume as 



