ZACATON AS A PAPER-MAKING MATERIAL. 
23 
very little trouble and producing a machine-finished sheet of good 
appearance and quality. Physical tests on this sheet, designated as 
No. 41, are recorded in Table VIII. 
Since the installation of a rotary type of digester by this bureau, 
further tests were made on Epicampes under the more favorable 
conditions afforded by this method of treatment. The rotary 
measured 6 feet in length by 4 feet in diameter, and was supplied 
with a large man head, thermometer well, pressure gauge, steam 
inlet, and steam relief through the hollow trunnions, and rotated at 
one-half a revolution per minute (fig. 12). A charge of 350 pounds 
could be handled conveniently, using a much stronger caustic solu- 
tion and yielding a more uniform pulp. 
The cooked charge was dumped into an iron drain tank under- 
neath, where, by means of a false bottom, the fiber could be drained 
and washed with no loss. By means of a vacuum under the false 
bottom, the water could be drained from the fiber uniformly, leaving 
only 70 to 80 per cent of water in the fiber, in which condition it 
could be sampled and weighed with a good degree of accuracy. 
Uniformity of chemical action on the grass was very noticeable and 
assisted very much in the subsequent operations and quality of the 
pulp. 
The grass used for these tests was of good, medium quality and in 
perfect condition. Four cooks were made, in order to secure suffi- 
cient pulp for a fair trial on the beating engine and paper macliine, 
the cooking conditions of which are shown in Table VI. 
Table VI. — Conditions of trials of four cooks of zacaton-pulp. 
Grass. 
Rela- 
Caustic 
solu- 
tion 
added. 
Maximum temperature, 
boiling. 
Cook. 
Air 
dry. 
Bone dry. 
tion of 
caustic 
soda 
Strength 
of caustic 
solution. 
Caustic 
soda 
added. 
Time 
Heat 
used. 
Time 
held. 
Per 
cent. 
Pounds. 
added. 
to 
reach. 
No. 11 
Pounds. 
341 
90.7 
309 
Per ct. 
19.0 
Per cent. 
9.18 
Pounds. 
58.9 
Gallons. 
77 
Hours. 
If 
° C. 
160 
Hours. 
6 
No. 12 
361 
91.0 
328 
20.1 
9.18 
66.0 
86 
2 
166 
160 
4 
No. 13 
335 
90.8 
304 
. 
20.2 
9.18 
61.6 
81 
If 
If 
166 
166 
4 
No. 14 
342 
90.8 
311 
20.3 
9.18 
63.2 
82 
166 
3| 
As seen by the table, the cooking was controlled by temperature 
instead of by steam pressure. Since it is temperature and not 
pressure which induces chemical action, and since steam pressure is 
indirectly an expression of temperature, it is obviously correct to 
employ either for control. On account of the presence of more or 
less air in the steam supply, and on account of gases which are 
