GROUND-WOOD PULP. 



47 



tion of certain grades of paper. The yield per hundred cubic feet is 

 very high, approximately 2,950 pounds, or 550 pounds more than 

 that from an equal amount of spruce. On the basis of a rough cord, 

 however, this difference would bo materially reduced, since white 

 birch logs have a thick bark and are often crooked. 



Black gum (Nyssa sylvatica) yields a fiber that in many ways 

 resembles that obtained from white birch. It is extremely short, 

 but forms a tougher sheet than coniferous fibers of the same length. 

 Considerable power must bo expended to produce laps that can be 



Fig. 35. — Western yellow pine (Pinus pondcrosa). 



taken off the wet machine satisfactorily. The pulp is not promising 

 from a news-print standpoint, but could be used as a filler or mixed 

 with pulp of a better grade. In color it is very white, ranking high 

 in this respect among the woods tested. Steaming the wood prior to 

 grinding gives a stronger pulp, but not to the extent observed in the 

 case of birch similarly treated. The yield of pulp from black gum is 

 approximately 2,600 pounds per hundred cubic feet of solid rossed 

 wood. 



