SUITABILITY OF LONGLEAF PINE FOE PAPER PULP. 5 
two butt logs (15 and 22 inches diameter) of the Louisiana wood, 
including all of the sapwood and heartwood. These logs were quite 
resinous, but were free from knots. They had an average bone-dry 
weight of 35.5 pounds per cubic foot green volume. The maximum 
and minimum weights were 40.1 and 32.3 pounds, respectively, for 
the various determinations. 
The material was prepared for cooking by removing the bark 
and sawing the pieces across the grain into sections five-eighths inch 
thick, which were then split into chips about three-sixteenths to 
one-fourth inch by 2 to 6 inches across the grain. The chips were 
screened to remove sawdust, and each lot was thoroughly mixed so 
as to be uniform throughout. 
APPARATUS. 
The semicommercial cooks were made in a vertical, stationary 
digester * consisting of a cast-steel cylindrical shell with top and bot- 
tom cones, with a capacity of about 62 gallons. The digester was fitted 
at the top with a " relief" or vent pipe, a pressure gauge, and a 
thermometer; and at the side with a gauge glass for noting the 
height of the liquor. The bottom was arranged for " blowing" the 
contents after cooking. Heat was furnished partly by passing steam 
directly into the digester at the bottom and partly by two steam 
coils placed inside the bottom cone. The pressure and temperature 
were regulated by admitting either more or less steam into the diges- 
ter and by relieving any excess pressure by means of the top vent. 
The autoclave cooks were made in a horizontal rotary autoclave 
with a capacity of about 2 gallons. This vessel was made of a 6-inch 
steel pipe with blank flange ends, fitted with trunnions, to one of 
which was attached a pressure gauge. A screw-joint handhole 
opening in the side provided for charging. Heat was furnished by 
Bunsen-burner flames underneath the autoclave, and the pressures 
were regulated by increasing or decreasing the heat. The autoclave 
was not relieved during cooking, and no observations of tempera- 
tures were made. The cooked pulps were not blown, as in the case 
of the semicommercial tests, but the cooking vessel was quickly 
cooled and the contents poured out. 
PROCEDURE IN TESTING. 
The liquor charges for the sulphate cooks were prepared by mixing 
caustic soda and sodium sulphide solutions of known composition, as 
determined by previous analyses, together with water and dry sodium 
sulphate. The amounts of each constituent were taken in such 
proportions that when the whole mixture was charged, with the chips, 
1 The apparatus used in the semicommercial cooks is practically the same as that fully illustrated and 
described in U. S. Department of Agriculture Bulletin No. 80, "Effects of Varying Certain Cooking Con- 
ditions in the Productions of Soda Pulp from Aspen,'' by Henry E. Surface, 1914. 
