SUITABILITY OF LONGLEAF PINE FOR 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 gaUons. 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' 7 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. 



