Page:Zacaton as a paper-making material (IA zacatonaspaperma309bran).pdf/19

 ZACATOX AS A PAPER-MAKING MATERIAL.

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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 obtained from these two cooks.