24 BULLETIN 72, XT. S. DEPARTMENT OF AGRICULTURE. 
Table 10. — Effect of varying initial concentrations on the yield of pulp. 
Weight of chips charged (bone-dry basis) pounds. . 0. 964 to 1. 031 
Water in chips per cent. . 16. 4 to 24. 4 
Causticity of liquor charge do 52. 8 to 53. 6 
Smphidity of liquor charge do 27. 2 to 27. 5 
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 2.5 
Maximum gauge pressure per square inch pounds. . 90 
Total duration of beater treatment (at light brush only) hours. . 2 
First Second 
Chemicals charged per 100 pounds of chips (bone-dry basis): series, series. 
NaOH pounds. . 15. 12. 
Na 2 S do.... 7.5 6.0 
Na 2 S0 4 do. ... 7. 5 6. 
All sodium compounds as Na 2 do 21. 8 17.5 
FIRST SERIES. 
Cook 
No. 
Liquor charge, initial concentrations. 
Initial volume 
of digester 
liquors per 
pound of chips 
(bone-dry basis). 
Yield of 
crude pulp 
(bone-dry 
basis). 
NaOH. 
Na 2 S. 
Na 2 S0 4 . 
All sodium 
compounds 
as Na 2 0. 
Grams 
Grams 
Grams 
Grams 
per liter. 
per liter. 
per liter. 
per liter. 
Gallons. 
Per cent. 
89 
60.0 
30.0 
30.0 
87.2 
0.300 
47.9 
90 
45.0 
22.5 
22.5 
65.1 
.400 
53.3 
91 
36.0 
18.0 
18.0 
52.1 
.500 
55.2 
93 
30.0 
15.0 
15.0 
43.6 
.600 
58.6 
94 
25.7 
12.9 
12.9 
37.4 
.^00 
61.3 
95 
22.5 
11.2 
11.2 
32.7 
.800 
64.4 
96 
20.0 
10.0 
10.0 
29.0 
.900 
66.4 
97 
18.0 
9.0 
9.0 
26.1 
1.000 
66.9 
SECOND SERIES. 
112 
72.0 
36.0 
36.0 
104.9 
0.200 
51.0 
100 
49.7 
24.8 
24.8 
72.0 
.290 
51.1 
101 
36.0 
18.0 
18.0 
52.2 
.400 
52.3 
105 
28.8 
14.6 
14.4 
42.2 
.500 
56.0 
114 
24.0 
12.0 
12.0 
35.0 
.600 
62.6 
106 
20.6 
10.3 
10.3 
30.0 
.700 
69.6 
107 
18.0 
9.0 
9.0 
26.2 
.800 
66.0 
108 
16.0 
8.0 
8.0 
23.3 
.900 
67.4 
115 
14.4 
7.2 
7.2 
21.0 
1.000 
67.3 
110 
12.0 
6.0 
6.0 
17.5 
1.200 
67.8 
111 
10.3 
5.1 
5.1 
15.0 
1.400 
67.4 
(P. L.— 138, S. L.— 176.) 
When the concentration of all sodium chemicals expressed as 
Na 2 was varied from 26.1 to 87.2 grams per liter (first series of 
tests) the resultant yield decreased from 66.9 to 47.9 per cent. The 
best results, considering both yield and quality of pulps, were obtained 
from cooks 91 and 93, using Na 2 concentrations of 52.1 and 43.6 
grams per liter, respectively. Pulps produced from cooks having 
lower concentrations were brittle and lacked strength and wearing 
properties. In the second series of tests, using somewhat smaller 
amounts of chemicals, the higher concentrations afforded the better 
results. The best pulp with regard to strength and wearing proper- 
ties was that obtained from cook 112, using a Na 2 concentration of 
104.9 grams per liter. The pulps obtained when using a concen- 
tration of 35 grams per liter or less were quite brittle, and had little 
strength and poor wearing properties. 
