UTILIZATION OF AMERICAN FLAX STEAW. 
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 VI. — List of bleaches, showing 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. 
Table VII. — List of bleaches, showing the extent of injury to fiber through 
insufficient lime. 
Lime, 
used. 
Time of 
treat- 
ment. 
Pressure 
per 
square 
inch. 
Waste liquor (per liter). 
Tensile 
strength of 
Cook No. 
Acidity. 
Soluble 
lime salts. 
ultimate 
fiber per 
square mm. 
of solid 
cross 
section. 1 
243 
Per cent. 
12 
14 
16 
18 
18 
Hours. 
6 
6 
6 
6 
6 
Pounds. 
100 
100 
100 
100 
100 
Grams, acetic 
acid. 
2.11 
.97 
( 2 ) 
Per cent, CaO. 
0.006 
.03 
Grams,CaO. 
7.4 
9.1 
7.0 
7.0 
7.5 
Grams. 
244 
57,000 
65,000 
245 
251 
252 
85,000 
Determined by a method devised by this laboratory. 
2 Barely alkaline. 
