In the latter case the raw wood is subjected to chemical treatment which
destroys all resinous and foreign matters, leaving merely the cellular
tissue, which, it is found, does not differ in substance from the cell
tissue obtained after treating rags. In either case this cellular
tissue, through the treatment to which the raw material is subjected,
becomes perfectly plastic or moldable, and while the paper made from one
differs slightly in certain characteristics from the paper made from the
other, they are nevertheless very similar, and it might be safe to
predict that further perfecting of processes will eventually make them
practically alike.
The woods used for this purpose are principally poplar and spruce, and
there are three classes of the wood pulp: (1) mechanical wood, (2) soda
process wood, and (3) sulphite wood pulp. The first method was invented
in Germany in 1844. The logs are hewn in the forest, roughly barked, and
shipped to the factory, where the first operation is to cut them up by
steam saws into blocks about two feet in length.
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