Page:Zacaton as a paper-making material (IA zacatonaspaperma309bran).pdf/20

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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.