40 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 
(11) Aspen may be successfully cooked with a mmimum of from 
20 to 25 pounds of caustic soda charged per 100 pounds of wood. 
The amount of this chemical actually consumed in the production 
of well-cooked bleaching pulps varies from 18 to 24 pounds per 100 
pounds of wood. 
PRACTICAL VALUE OF RESULTS. 
The experiments discussed in this bulletin have shown in detail 
the effects of certain cooking conditions on the yields and properties 
of the resultant pulp, on the efficiency of the cooking chemicals, and 
on various items affecting costs of production. From a study of 
these results it should be possible for a mill operator so to regulate 
the cooking process as to secure the largest possible yield of pulp of 
the desired quality at a minimum cost for chemicals, fuel, labor, and 
overhead charges hi so far as the operation is affected by the cooking 
conditions considered. 
The clear, sound wood used in the experiments afforded yields of 
good pulp from 10 to 25 per cent higher than the better run of the 
yields reported by pulp mills. Moreover, some of these experimental 
yields were obtained with shorter cooking periods and less chemicals 
than are employed commercially. Although the laboratory results 
may not be equaled in mill practice, the possibility of greatly 
increased efficiency in the process of converting wood into soda pulp 
is indicated. 
