UTILIZATION OF AMERICAN" FLAX STEAW. 7 



The laboratory work consisted of pulping tests, beating and wash- 

 ing the pulp and making it into hand sheets. From the data gathered 

 during this process and from the samples conclusions were drawn 

 as to procedure and conditions to be employed on subsequent semi- 

 commercial tests. It is fully realized that in general it is impossible 

 to duplicate commercial working conditions on a small laboratory 

 scale ; therefore, laboratory results, valuable as they may be, should 

 be interpreted commercially onty with extreme caution. The follow- 

 ing laboratory work and results are regarded, therefore, as approxi- 

 mate indications, to assist in subsequent semicommercial tests. 



The flax straw used in these tests was of the ordinary seed-flax 

 type raised in the vicinity of Fargo, N. Dak., was thrashed Avith the 

 ordinary thrashing machine, as is the practice in that section, and 

 was baled in an ordinary hay baler. The bales contained their proper 

 complement of chaff, usually 30 per cent, and averaged 80 pounds in 

 weight. 



To serve as a fiber suitable for paper manufacture it is necessary 

 to reduce the woody portion by cooking or bleaching to such a condi- 

 tion that the beater will be able to disintegrate mechanically or 

 separate the woody shives to such a size or condition that they may 

 be removed from the true fiber by washing in the regular manner. 

 The proportion of woody matter that it is necessary to remove de- 

 pends naturally en the grade of product desired. 



Pulping tests, technically known as " bleaches," were conducted in 

 an iron rotary boiler of 10 gallons capacity, heated by means of direct 

 steam and gas burners, and rotating 1 revolution per minute. 



In conducting a bleach, the boiler is charged full of straw, from 

 which a sample has been drawn for a moisture determination, in 

 order to calculate the weight of bone-dry straw employed. The pre- 

 determined quantity of lime (burned lime), calculated in percentage 

 of the bone-dry straw, is added in the form of milk of lime, together 

 with sufficient water to amount to 1 gallon per 2| pounds of straw. 

 After closing the boiler and rotating a few times, direct steam at 110 

 pounds pressure is admitted, the gas urners underneath are lighted 

 in order to counteract excessive radiation, and the charge is heated to 

 a certain point in one hour. 



The control of the degree of heat in a boiler is accomplished in 

 practice by a steam-pressure gauge which bears a direct relation to 

 the temperature of the charge, but since it is not pressure but tem- 

 perature which induces (lie chemical actions, it would obviously be 

 us correct to employ temperature :is pressure for ;i guide. In all of 



the Laboratory work the temperature control was used, being effected 



by a thermometer inserted in a horizontal well extending from (he 



end of the hoiler to the center of the charge. After the desired tem- 



