——
.
BULLETIN
14
300,
U.
S.
DEPARTMENT OF AGRICULTURE.
Table
Fiber yields from two bone-dry cooks of zacaton grass, using different concenI. trations of caustic soda under a steam pressure of 90 pounds to the square inch. Caustic soda.
Quan-
Cook.
Percent-
Per
tity.
liter.
Cook No.
3
boiled.
24.4 23.0
was made
Screen- Screened ings.
Pounds.
Hours.
19.7 29.0
404 400
Pressure.
age.
Gra ms. Grams.
No. 1 No. 2
Yield.
Time
Per
90 90
6
H
in the rotary
ct.
Per
4.7 4.6
by
Pith.
fiber.
Per
ct.
35.4 37.1
Total fiber.
Per
ct.
7.
Long fiber.
Per
ct.
27.9
5
treating 2,400
ct.
40.1 41.7
grams
of
bone-dry weight, with 19 per cent of caustic soda at a concentration of 71 grams per liter for 6 hours at a steam pressure of 80 pounds per square inch, which gave a yield of 50.8 per cent of The pulp was very uniform, soft, and of good appearance, total fiber. and the cooking conditions were not as harsh or expensive as those for commercially treating poplar wood. Cook No. 4 was made from a bale of zacaton which was received in a dry but very moldy condition, and the grass was quite brittle. A charge of 2,400 grains was treated with 19 per cent of caustic soda at a concentration of 70 grains per liter for 6 hours at a steam pressure of 80 pounds per square inch, giving a yield of 49 per cent of total fiber. It was impossible to distinguish any difference in quality between the pulp from the sound and that from the moldy grass, the fungi apparently attacking only the less resistant forms of hemigrass,
celluloses.
Cook No. 5 was made by treating 2,000 grams of zacaton with 18 per cent of caustic soda at a concentration of 70 grams per liter for 5 hours at a steam pressure of 90 pounds per square inch, giving a yield of 44.6 per cent of total fiber.
Cook No. 6 was made by treating 2,400 grams of grass with 16 per cent of caustic soda at a concentration of 70 grams per liter for 5^ hours at a steam pressure of 90 pounds per square inch, giving a fiber
The expenditure
yield of 47.7 per cent of the total bone-dry grass.
soda and time was very moderate, the yield was very general appearance of the pulp was remarkably good. of
MICROMEASUREMENTS OF FIBER AND OTHER
and the
fair,
CELLS.
Table II shows the comparative measurements of the cells of zacaton grass. The measurements were made on the screened stock from which paper No. 76 was made. Table
II.
Comparison of the
cell
Parenchyma of pith
measurements of fibers and other Long epidermal cells.
cells
of zacaton grass.
Parenchyma.
Bast.
Measurement.
Maximum Minimum Average
Length.
Width.
Length.
Width.
Length.
Width.
Length.
Width.
Mm.
Mm.
Mm.
Mm.
Mm.
Mm.
Mm.
Mm.
0.112 .072 .092
072 .057 .061
0.
079 .072 .075
0.
011 .011 .011
0.
223 .162 .193
0.
05S .018 .038
0.
3.0
L7
013 .005 .0085
0.
