ZACATOX AS A PAPER-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 Xo. 2, 400 grams of grass were treated with 23 per cent of 
caustic soda at a concentration of 29 grams per liter for 7h 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 miiform 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, 12J 
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 well 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. 
