per making for
almost two thousand years.

In the ordinary book papers of to-day the materials used are largely
rags and wood fibres. "Esparto," a Spanish grass, is used in England
to a great extent, but it is too expensive to import to this country,
and is, therefore, not used here. Many other materials could be used
to advantage, such as "bagasse," the waste material of sugar cane, and
corn stalks, both of which make good book paper; also hemp, wild
clover, and other plants which have a good fibre.

Only two kinds of rags are used, linen and cotton, of both of which
there are several grades. Linen rags make a very strong paper, and are
mostly used in manufacturing fine writing papers, ledgers, and covers
for books where strength is necessary. Cotton rags may be divided into
three distinct kinds, whites, blues, and colors, and these in turn are
subdivided into several grades. Most of the blue rags are now imported
from Germany, Belgium, and France; none from Japan as formerly. The
whites and colors are bought in this country.

Wood fibres are divided into two classes, the harder woods, such as
spruce, fir, etc., and the softer, such as poplar, cottonwood, etc.
There are three ways of reducing or disintegrating wood fibres: first,
by sulphurous acid or bi-sulphite of lime fumes, which gives the name
"sulphite fibre"; second, by caustic soda, which is called "soda
fibre"; and third, by grinding. The last is usually only used for
stock in very low grades of paper, such as newspaper and wrapping
paper; it is rarely used for book paper. Many persons think that this
ground wood, which is merely spruce ground very fine into pulp, is
used in book papers; but if it were, the paper would not last long,
and would almost immediately discolor on exposure to light and air.
There is a theory that no paper made from wood fibres is lasting, and
that therefore high grades of paper for fine books should be made
only of rags, but this is erroneous, for wood stock and rag stock
nowadays are treated and prepared in the same way, and only
practically pure cellulose matter goes into the paper. It would be a
different matter, however, if _ground_ wood were used for fine papers,
for in this stock the cellulose matter is not separated.

Rags are usually purchased by the paper manufacturer in solid bales,
which have been graded into whites, blues, or colors. After being
opened, they are thrown into a thrashing machine, which thrashes and
sha