ZACATON^ AS A PAPEE-MAKING MATERIAL. 



13 



grams of caustic soda per liter for 6 hours at a steam pressure of 90 

 pounds per square inch.. It was very apparent that the long fiber, 

 and even the screened fiber, was superior in quality to that of many 

 other fibrous plants which had been tested, the soft feeling and 

 bright luster being very noticeable. 



In cook No. 2, 400 grams of grass were treated with 23 per cent of 

 caustic soda at a concentration of 29 grams per liter for 7^ hours at a 

 steam pressure of 90 pounds per square inch. The yield and general 

 appearance of the fiber from this cook were very similar to those of 

 the one preceding, and the conditions of treatment were possibly all 

 that could be desired with this type of digester. Further economy of 



Fig. 10, — Experimental rotary pulp boiler. 



treatment might be obtained with the rotary type of digester, where 

 a lower percentage of caustic soda and a smaller volume of solution 

 in proportion to the grass used would be possible. This method 

 gives a more uniform pulp and affords a somewhat cheaper recovery 

 of the spent soda, which is essential to the economic application of 

 the soda process. 



The rotary type of boiler employed was a J-inch steel shell, 12 J 

 inches in diameter by 29| inches in length (38 liters in capacity), 

 supplied with a hand hole and screw cap and mounted so as to rotate 

 on its long horizontal axis one revolution per minute. (Fig. 10.) 

 The charge was heated by gas burners underneath and controlled by 

 a thermometer inserted in a weU extending from the end of the shell 

 into the center of the charge. Table I shows the yield of fiber ob- 

 tained from these two cooks. 



