28 
BULLETIN 80, TJ. S. DEPARTMENT OF AGEICULTUEE. 
of consumption and subsequently decrease of percentage efficiency 
are indicated. While the possibility of error is not eliminated, 1 this 
result indicates the need for further investigation. 
RELATION BETWEEN CAUSTIC SODA CONSUMED AND YIELDS. 
For the purpose of further studying the cooking effects of the 
various conditions employed, yields of total crude pulps from all of 
the cooks were platted against amounts of caustic soda consumed 
per 100 pounds of wood charged (fig. 14). The average curve drawn 
through these points indicates a definite relation between yields and 
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TEST VARYING 
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10 12 14 16 18 20 22 24 26 28 30 32 34 
NaOH CONSUMED PER 100 PDS.0F BONE DRY W00D-PDS. 
Tig. 14.— Relation between yields and amount of caustic soda consumed. 
amounts of caustic soda consumed, regardless of the cooking condi- 
tions. However, even if it is assumed that the location of some of the 
points is due to experimental errors, the relation, as regards individual 
cooks, can be only an approximate one, since it has already been 
pointed out that in some of the tests increased cooking effects were 
obtained without any increase in the consumption of caustic soda. 
If the curve were produced for lower amounts of caustic soda, the 
yields would probably be somewhere between 80 and 100 per cent 
at zero consumption, since under these conditions cooking could still 
be effected by water alone. 2 
i The test data show a loss of digester liquor overflowing through the "top relief" for cooks 25 and 26 
(that for cook 26 showing the greatest loss), and it is due to the platted points for these two cooks that the 
curves indicate greater consumption of caustic soda at the lower concentrations. 
2 See Tauss's experiments, Table 1. 
