caustic soda upon vegetable
fibers.

Braconnot, in 1820, obtained alumina by treating wood with an alkali,
but the first application of wood to the manufacture of paper was due
to Chauchard. By boiling vegetable fibers with caustic lyes, Collier
and Piette obtained cellulose. Again, in 1862, Barne and Blondel
proposed to make cellulose in a similar way, but employed nitric acid
in the place of soda.

The first cellulose made exclusively from wood and caustic soda was
produced at the Manayunk Wood Pulp Works, in 1854, in the neighborhood
of Philadelphia, by Burgess & Watt. The operation consisted in
treating the wood for six hours at a pressure of from six to eight
atmospheres, with a solution of caustic soda of 12 deg. B.

Ungerer noticed that it was sufficient to limit the pressure from
three to six atmospheres, according to the quality of the wood, and
advised the use of solutions containing four to five per cent. of
caustic soda. He employed a series of cylinders, arranged vertically,
in which the wood was subjected to a methodical system of lixiviation.
The same lye passed through many cylinders, so that when it made its
exit at the end it was thoroughly exhausted, and the wood thus kept
coming in contact with fresh alkaline solutions.

According to the account of Kiclaner, the disintegration of wood may
be effected in the following four ways:

1. By heating direct in boilers at a pressure of 10
atmospheres. (See Dresel and Rosehain.)

2. In vertical boilers heated direct or by steam, and kept at
a pressure of from 10 to 14 atmospheres. (Sinclair, Nicol, and
Behrend.)

3. In revolving boilers, maintained at a pressure of 12
atmospheres by direct steam.

4. By means of a series of small vessels communicating with
each other, and through which a lye circulates at a pressure
of six atmospheres. (Ungerer.)

This latter process is preferable to the others.

Researches have also been made by the author in order to ascertain the
loss which wood and cellulose suffer at different temperatures or in
contact with varying quantities of alkali (NaHO).

The following is a _resume_ of the experiments, giving the loss in per
cent. resulting from a "cooking" of three hours duration:

I. Ordinary pressure:
10 grms. cellulose, with 580 c.c. of caustic
soda solution, sp. gr. 1.09 21.99
10 grms. of soft wood, treated as above 49.19