PRODUCING SODA PULP FROM ASPEN. 
19 
1000 
1 
t\ 
800 
\ 
400 
V 
»8 
\ 
-a 
°- 
V 
£ — 
eL-S. 
.10 
.20 .30 .40 
POUNDS NaOH PER POUND OF WOOD 
800 
600 
The more thorough cooking resulting from the higher initial con- 
centrations of caustic soda produced lighter-colored pulps, although 
the lower limit of (he cooking condition in these tests was considerably 
above the minimum for successful cooking. 
While the several curves shown in figure 5 indicate for each group 
of tests more or less change in the "parts black" color ratings or the 
depth of color, the hues of the 
pulps were not materially 
affected. 
OCCURRENCE OF SHIVES. 
Shives are most numerous 
in pulps from the less severe 
cooks and are entirely absent 
from those thoroughly cooked. 
The shives curves (fig. 6) bear 
some resemblance to those for 
the yields of screenings, but 
shives disappear from the pulps 
only under somewhat more 
severe cooking conditions than 
those which reduced the yield 
of screenings to zero. At the 
point of maximum yield of 
screened pulp the cooking has 
progressed far enough for the 
fibers to become more or less 
separated from each other, but 
not completely so, since some 
of them still remain in groups 
(shives) small enough to pass 
the screen slots. But as the 
cooking becomes more severe 
the fibers are entirely sepa- 
rated, and the resulting pulp 
is free from shives. In gen- 
eral, increasing the amount of 
temperature of cooking, or the 
liquor decreases the "shiviness" 
400 
200 
\ 
\ 
\ 
\ 
V 
13 
JSL 
■JL 
2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 
22 < 
>v^ 
I 
,20 II9 
>!R™H 
17 
70 80 B0 100 110 120 
• MAX. PRESSURE-PDS. PER SQ. IN. 
26* 
25 
—£ 
23 
200 
°e 
200 
40 50 60 70 80 90 100 110 
CONCENTRATION NaOH-GRAMS PER LITER 
Fig. 6. — Effects of cooking conditions on the occur- 
rence of shives in pulp. 
caustic soda, the duration or the 
initial concentration of the digester 
of the pulp. 
ASH CONTENT. 
The curves in figure 7 indicate that increasing the thoroughness 
of cooking within certain limits decreases the ash content of the pulp-; 
outside of these limits the ash content may be increased. 
Since the normal amount of ash in aspen wood is not over three- 
quarters of 1 per cent, the high amounts in the pulps produced 
