SUITABILITY OF LONGLEAF PINE FOR PAPER PULP. 



19 



The yields shown in Table 6 varied from 65.7 per cent for 14.5 

 pounds of total Na 2 O per 100 pounds of wood to 36.8 per cent for 

 72.5 pounds of total Na 2 O. The conditions indicated for cook 31 

 afforded the best results with regard to both yield and quality of 

 pulp produced. With the higher yields the pulps were harsh and 

 had less resistance to wear. Nevertheless, wrapping papers of 

 medium grades could be made from these pulps. The pulp from 

 cook 30 was of good quality, with strength and wearing properties 

 equal to that from cook 31, but the yield was not so high. Cooks 

 43, 26, and 38 were duplicates of each other, and show the accuracy 

 attained in the yield determinations. The pulps from these three 

 cooks were soft and fluffy, and had poor strength and wearing prop- 

 erties, due to overcooking. 



TABLE 6. Effect of varying amounts of all sodium compounds on the yield of pulp. 



Weight of chips charged (bone-dry basis) pounds. . 0. 996 to 1. 007 



Water in chips per cent. . 10. 2 to 11. 5 



Causticity of liquor charge do. ... 53. 2 to 54. 3 



Sulphidity of liquor charge do 27. 4 to 27. 9 



Initial volume of digester liquors per pound of chips (bone'-dry basis) gallons. . 0. 675 to 0. 683 



Duration of cooking, total hours. . 3. 



Duration of cooking, at zero gauge pressure do 0. 1 



Duration of cooking, at maximum gauge pressure do 2.0 to 2.3 



Maximum gauge pressure per square inch pounds. . 90 



Total duration of oeater treatment (at light brush only) hours. . 0, 1, or 2 



(P. L. 138, S. L. 36.) 



1 The Na2O values for cooks 26 and 38 differ mainly because of different amounts of NajCOg which are not 

 separately recorded in the table. 



EFFECTS OF SODIUM CHLORIDE. 



A few tests were made to determine whether or not the use of 

 sodium chloride in conjunction with caustic soda would result in firmer 

 and less fuzzy pulps, more resistant to wear, than are ordinarily pro- 

 duced with the soda process. If this were possible a process might be 

 developed to produce pulps similar to those obtained with the sulphate 

 process without the disagreeable odors so characteristic of it. Table 7 

 shows a comparison between cooks made with caustic soda alone and 

 with caustic soda and sodium chloride. It is not probable that sodium 



