Page:Zacaton as a paper-making material (IA zacatonaspaperma309bran).pdf/29

 — 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 further tests were

conditions

by this bureau, the more favorable treatment. The rotary

made on Epicampes under by

afforded

method

this

of

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 solution and yielding a more uniform pulp. The cooked charge was dumped into an iron drain tank under-

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 neath, where,

pulp.

was of good, medium quality and in Four cooks were made, in order to secure sufficient pulp for a fair trial on the beating engine and paper macliine, the cooking conditions of which are shown in Table VI.

The

grass used for these tests

perfect condition.

Table VI.

Conditions of

trials

offour cooks of zacaton-pulp.

Maximum

Grass.

temperature,

boiling.

Rela-

Bone dry.

Cook. Air dry.

tion of caustic

soda added.

Per cent.

Strength

Caustic

of caustic soda solution. added.

Caustic solu-

tion

added.

Pounds.

Per

Pounds.

ct.

Time to reach.

Per

cent.

Pounds. Gallons. Hours.

No. 11

341

90.7

309

19.0

9.18

58.9

77

If

No. 12

361

91.0

328

20.1

9.18

66.0

86

2

No. 13 No. 14

335 342

90.8 90.8

304 311

20.2 20.3

9.18 9.18

61.6 63.2

81

If If

.

82

Heat

Time

used.

held.

°

C.

160 166 160 166 166 166

Hours. 6 4 4 3|

As seen by the table, the cooking was controlled by temperature Since it is temperature and not instead of by steam pressure. 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