In connection with the manufacture of cellulose, it is also interesting to prosecute at the same time experiments with solutions of the caustic alkalies, in order to study the mode of action upon both wood and pure cellulose.  The manufacture of cellulose has for many years been an industry, and yet little or nothing from a chemical point of view is known of the action of 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: