WOOD PULP AND PAPER 



25 



since the fibers are much shorter and weaker. Inasmuch as the fibers 

 easily become broken in grinding, it is not adapted for reduction by the 

 mechanical process. However, hemlock is available in large quantities 

 and can be successfully reduced by the chemical process for news, wrap- 

 ping and other cheaper grades of paper. 



Poplar, including the two aspens of the northeast and Canada, ranks 

 third in importance as a pulp wood. It forms about 8 per cent of the 

 total supply. The wood is soft, light in weight and color, but its fibers 

 are short and comparatively weak. It is reduced almost entirely by the 

 soda process and its pulp is mixed with sulphite pulp to give it sufficient 

 strength for manufacture into grades of book paper. 



Photograph by A. M. Richards. 



FIG. 2. A pulp mill with a capacity of 60 tons of No. i and No. 2 bleached and natural 

 spruce and hemlock sulphite pulp in twenty-four hours. The tall building on the right 

 contains the digester and bleaching rooms. The building in the right foreground is 

 the wood room for rossing, splitting, chipping and screening. 



Balsam fir is very commonly mixed with spruce and used as such for 

 mechanically ground pulp. Purchasers of pulpwood usually specify 

 that no large per cent of the wood purchased shall be of balsam fir. The 

 wood is light in color and weight, soft and comparatively free from resins, 

 gums, and other objectionable materials. Papermakers object to it, 

 however, because it is said that the pitch from it covers the felts and 

 cylinder faces making operations difficult. Balsam fir is available in 

 fairly large quantities in the northeast and eastern Canada. It is largely 

 reduced by the mechanical process, and finds a large market for news- 

 paper stock; it is said, indeed, that balsam fir finds its greatest economic 



