~~ 
445 
are present. The readiness with which it is reduced to the condition of 
paper pulp, the kind and strength of chemicals required, and the time 
necessary for proper digestion likewise depend on this same factor. The 
fibrous waste was prepared for experimentation in much the same man- 
ner as old rope or rags are treated—namely, it was cut by hand into short 
pieces, thoroughly cleaned from all adhering sand and dirt and digested 
with caustic-soda liquor at elevated temperatures. The residues were 
drained and washed with hot water until they were free from alkali and 
the washings were colorless; they were then dried to constant weight in 
a water-jacketed air bath. 
Experiment No, 1.—Strength of liquor, 2 per cent; 17 per cent caustic soda 
calculated on weight of material digested; pressure, 6-8 atmospheres; time, 44 
hours; yield, 36.65 per cent; residue, brown-gray in color, not entirely free 
from cellular matter. 
Jeperiment No. 2.—Strength of liquor, 3 per cent; 25 per cent caustic soda 
calculated on weight of material; pressure, 6-7 atmospheres; time, 43 hours; 
yield, 32.84 per cent ; well-cooked pulp of a light-gray color. 
Experiment No. 3.—Strength of liquor, 3} per cent; 30 per cent caustic soda 
calculated on weight of material; pressure, 6-7 atmospheres; time, 5 hours; yield, 
31,7 per cent. 
Haperiment No. 4.—Strength of liquor, 43 per cent; 40 per cent caustic soda; 
other conditions same as No. 3; yield, 31.64 per cent. 
Experiment No, 5.—Five per cent liquor; 454 per cent caustic soda; other 
conditions same as above; yield, 31.51 per cent. 
The waste employed in the above experiments was obtained from a 
machine-stripping process. Reference to the table on page 443 shows 
the relatively high percentage of dry machine waste as compared with 
the hand-stripped article. This explains the low cellulose content ob- 
tained. The experiments bring out the following points: 
First. Two per cent liquor is insufficient with the pressure and time 
employed. 
Second. Three and three-fourths per cent liquor is as efficient as the 
stronger concentrations. 
Third. The gradual but constant lowering of the yield in experiments 
3, 4, and 5 is due to the fact that the stronger liquors attack the cellulose, 
but pressures of 6—7 atmospheres may safely be employed because, under 
these conditions, the solvent action is very slight. 
The conditions of time, pressure, and strength of caustic soda which 
give the best results are approximately one-half of those employed in the 
manufacture of wood pulp by the soda process. 
A second series of five digestions was made on abaca waste resulting 
from the hand process of extracting the fiber. The preliminary prepara- 
tion of the material was the same as in the preceding experiments. In 
each case a 34 per cent caustic soda solution was employed, 25 per cent 
‘austic calculated on the weight of the material digested. The pressure 
was held for five hours at 6 atmospheres as a minimum and 7 atmospheres 
as a maximum. The yields were 38.89, 41.69, 42.59, 42.66, and 42.14 
