14 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 
Table I. — Fiber yields from two bone-dry cooks of zacaton grass, using different concen- 
trations of caustic soda under a steam pressure of 90 pounds to the square inch. 
Caustic soda. 
Time 
boiled. 
Pressure. 
Yield. 
Cook. 
Quan- 
tity. 
Per 
liter. 
Per- 
cent- 
age. 
Screen- 
ings. 
Screened 
fiber. 
Pith. 
Long 
fiber. 
Total 
fiber. 
Gra ms. 
Grams. 
Hours. 
Pounds. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
No. 1 
404 
19.7 
24.4 
6 
90 
4.7 
35.4 
7. 5 
27.9 
40.1 
No. 2 
400 
29.0 
23.0 
H 
90 
4.6 
37.1 
41.7 

Cook No. 3 was made in the rotary by treating 2,400 grams of 
grass, bone-dry weight, with 19 per cent of caustic soda at a con- 
centration 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 
total fiber. The pulp was very uniform, soft, and of good appearance, 
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 hemi- 
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 
yield of 47.7 per cent of the total bone-dry grass. The expenditure 
of soda and time was very moderate, the yield was very fair, and the 
general appearance of the pulp was remarkably good. 
MICROMEASUREMENTS OF FIBER AND OTHER 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 measurements of fibers and other cells of zacaton grass. 
Measurement. 
Parenchyma of pith . 
Long epidermal 
cells. 
Parenchyma. 
Bast. 
Length. 
Width. 
Length. 
Width. 
Length. 
Width. 
Length. 
Width. 
Maximum 
Minimum 
Average 
Mm. 
0.112 
.072 
.092 
Mm. 
0. 072 
.057 
.061 
Mm. 
0. 079 
.072 
.075 
Mm. 
0. 011 
.011 
.011 
Mm. 
0. 223 
.162 
.193 
Mm. 
0. 05S 
.018 
.038 
Mm. 
3.0 
L7 
Mm. 
0. 013 
.005 
.0085 
