UTILIZATION OF AMERICAN FLAX STRAW. 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 only 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 with 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 on 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 the chemical actions, it would obviously be 
as correct to employ temperature as pressure for a guide. In all of 
the laboratory work the temperature control was used, being effected 
by a thermometer inserted in a horizontal well extending from the 
end of the boiler to the center of the charge. After the desired tern- 
