SUITABILITY OF LONGLEAF 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 . . 3.0 
Duration of cooking at zero gauge pressure do 0. 1 
Duration of cooking at maximum gauge pressure do 2. 3 
Maximum gauge pressure per square inch •. pounds. . 90 
Total duration of beater treatment (at light brush only) hours . . or 1 
FIRST SERIES. 
Liquor charge. 
Chemicals charged 
per 100 
Initial concentrations. 
basis). 
Yield of 
Cook 
No. 
pulp 
(bone- 
All 
Caus- 
Sulphid- 
All 
sodium 
ticity. 
ity. 
sodium 
basis). 
NaOH. 
Na 2 S.i 
com- 
pounds, 
as Na 2 0. 
NaOH. 
Na 2 S.i 
com- 
pounds, 
asNa 2 0. 
Grams 
Grams 
Grams 
per liter. 
per liter. 
per liter. 
Per cent. 
Per cent. 
Pounds. 
Pounds. 
Pounds. 
Per cent. 
31 
26.3 
13.1 
38.1 
53.6 
27.5 
15.0 
7.5 
21.7 
52.0 
55 
52.1 
13.0 
57.9 
69.7 
17.9 
30.0 
7.5 
33.4 
42.9 
56 
69.6 
13.0 
72.0 
74.9 
14.4 
40.0 
7.5 
41.4 
39.6 
57 
87.0 
13.0 
85.6 
78.7 
12.1 
50.0 
7.5 
49.2 
42.1 
58 
104.4 
13.0 
99.7 
81.1 
10.4 
60.0 
7.5 
57.3 
40.0 
59 
121.8 
13.0 
113.6 
83.1 
9.1 
70.0 
7.5 
65.3 
33.3 
60 
156.6 
13.0 
139.3 
87.1 
7.4 
90.0 
7.5 
80.1 
27.7 
SECOND SERIES. 
. 29 
35.4 
44.4 
84.2 
32.6 
42.0 
19.9 
25.0 
47.4 
42.3 
28 
55.3 
45.9 
101.9 
42.1 
35.8 
30.0 
24.9 
55.2 
38.2 
33 
52.7 
43.9 
99.5 
41.0 
35.1 
30.0 
25.0 
56.6 
37.0 
54 
60.8 
43.3 
104.5 
45.1 
32.9 
35.0 
24.9 
60.1 
39.9 
32 
70.1 
43.9 
113.0 
48.5 
30.9 
39.9 
25.0 
64.4 
34.8 
27 
73.8 
45.9 
116.7 
49.0 
31.3 
40.0 
24.9 
63.3 
35.0 
53 
76.6 
43.3 
117.0 
50.8 
29.4 
44.1 
24.9 
67.3 
38.6 
43 
88.2 
44.3 
128.3 
53.2 
27.4 
49.8 
25.0 
72.5 
36.8 
26 
88.8 
44.4 
126.8 
54.3 
27.9 
50.0 
25.0 
71.4 
37.6 
49 
104.2 
43.4 
139.2 
58.0 
24.8 
60.0 
25.0 
80.2 
31.8 
52 
121.6 
43.2 
152.4 
61.9 
22.6 
70.0 
24.9 
87.8 
31.8 
51 
139.0 
43.5 
166.6 
64.6 
20.7 
80.0 
25.0 
95.8 
28.1 
With a few minor exceptions, the same values apply to the Na 2 SO< 
(P. L.— 138, S. L.— 36.) 
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 
