UTILIZATION OF AMERICAN" FLAX STRAW. 



19 



it is believed that they can be removed readily at the tow mills at a 

 very slight increase in the cost of processing the tow. 



A series of lime cooks or bleaches was made in the laboratory, em- 

 ploying a 38-liter rotary pulp boiler operated by direct steam, from 

 the results of which it was concluded that a treatment with 14 per 

 cent of burned lime for 4 hours at a steam pressure of 100 pounds 

 per square inch would give a product satisfactory for fiber-board 

 manufacture. Under this treatment, the yield of washed or sepa- 

 rated fiber was 48 per cent of the bone-dry weight of tow used. 



Table VI gives a partial list of the laboratory bleaches, illustrat- 

 ing the method of determining the correct amount of lime necessary 

 to be used. 



Table YL- 



-List of bleaches, shoicmg the method of determining the correct 

 amount of lime to be used. 



Cook No. 



Lime 

 used. 



Time of 

 treat- 

 ment. 



Pressure 

 per 



square 

 inch. 



Waste liquor (per liter). 



Acidity. 



Soluble 

 lime salts. 



246 



Per cent. 

 12 

 14 



15 

 17 

 17 



Hours. 

 5 

 5 



5 

 5 

 5 



Pounds. 

 100 

 100 



100 

 100 

 100 



Grams, acetic 

 acid. 

 0.97 

 .26 

 Per cent, CaO. 

 0.008 

 .023 

 .024 



Grams,CaO. 

 6.8 



247 



5.8 



248 



6.3 



249 



6.9 



250 



7.2 







The yield on cook No. 250 was 73.8 per cent of total fiber and 48.6 

 per cent of washed or separated fiber. Washing was done in the 

 beater by means of a regular washer covered with 30-mesh wire 

 cloth, such as is used in fiber-board mills. 



A series of bleaches on flax straw is recorded in Table VII, 

 showing the extent to which fiber can be injured by not employing 

 sufficient lime in the bleach. 



Tame VII. 



-List of bleaches, shoiving the extent of injury to fiber through 

 insufficient lime. 





Lime, 

 used. 



Time of 

 treat- 

 ment. 



Pressure 



per 



square 



inch. 



Waste liquor (per liter). 



Tensilo 

 strength of 



Cook Xo. 



Acidity. 



Soluble 

 lime salts. 



ultimate 

 fiber per 

 square mm. 

 of solid 

 cross 

 section. 1 



24a 



Per cent. 

 12 

 14 

 16 



18 



18 



6 

 6 

 6 



6 

 6 



/■nil/nl::. 



100 



100 

 100 



100 

 100 



Gramsj acetic 

 acid. 

 2.11 



.97 

 ( 2 ) 



l'i i it at., CaO. 



II.OOI, 



.03 



GramSjCaO. 

 7.4 

 9.1 

 7.0 



7.0 



Grams. 





57,000 





65,000 













86,000 







Determined by a method devised by tli 



• Barely alkaline. 



