Chemical wood pulp of the best quality makes an excellent product, and
is largely used for both print and book paper; it is frequently mixed
with rag pulp, making a paper that can scarcely be distinguished from
that made entirely from fine rags, though it is not of the proper
firmness for the best flat or writing papers. All ordinary newspapers,
as well as some of the cheaper grades of book and wrapping paper, are
made entirely from wood, the sulphite or soda process supplying the
fiber, and ground wood being used as a filler. In the average newspaper
of to-day's issue, twenty-five per cent of sulphite fiber is sufficient
to carry seventy-five per cent of the ground wood filler. The value of
the idea is an economical one entirely, as the ground wood employed
costs less than any other of the component parts of a print-paper sheet.
The cylinder machine, to which reference was made earlier in the
chapter, was patented in 1809 by a prominent paper-maker of England, Mr.
John Dickinson. In this machine, a cylinder covered with wire cloth
revolves with its lower portion dipping into a vat of pulp, while by
suction a partial vacuum is maintained in the cylinder, causing the pulp
to cling to the wire until it is conveyed to a covered cylinder, which
takes it up and carries it forward in a manner similar to the system
already described.
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