SUITABILITY OF LONGLBAF PINE FOR PAPER PULP. 



15 



EFFECTS OF VARYING AMOUNTS OF CAUSTIC SODA. 



The effect of varying amounts of caustic soda on the yield of crude 

 pulp is shown in Table 4. Two series of tests were made, differing 

 in the amounts of sodium sulphate and sodium sulphide employed. 

 In the first series increasing the amounts .of caustic soda from 15 to 

 90 pounds per 100 pounds of wood resulted in a decrease in the yield 

 of from 52 to 27.7 per cent. This decrease, however, was not directly 

 proportional to the increase of caustic soda used, as values of this 

 chemical between 30 and 50 pounds had little effect in varying the 

 yield. For higher and lower values the effect was quite pronounced. 

 In the second series a larger amount of sodium sulphide was used, 

 and consequently the yields were lower for corresponding amounts of 

 caustic soda, but variations in the amounts of this chemical produced 

 similar effects. 



TABLE 4. Effect of varying amounts of caustic soda (NaOH) on the yield of pulp. 



Weight of chips charged (bone-dry basis) pounds. . 0. 986 to 1. 007 



Water in chips per cent. . 10. 2 to 12. 6 



Initial volume of digester liquors per pound of chips (bone-dry basis) gallons.. 0.650 to 0.690 



Duration of cooking, total hours. . 



Duration of cooking at zero gauge pressure do 



Duration of cooking at maximum gauge pressure do 



Maximum gauge pressure per square inch pounds. . 



Total duration of beater treatment (at light brush only) hours . . 



3.0 

 0.1 

 2.3 

 90 

 Oorl 



FIRST SERIES. 



SECOND SERIES. 



(P. L. 138, S. L. 3b.) 



1 With a few minor exceptions, the same values apply to the Na 2 SO4. 



The best quality of pulp was obtained with cook 31, using 15 

 pounds of caustic soda per 100 pounds of wood. This resulted in a 

 slightly undercooked product, which came from the autoclave in the 



