In the soda process, invented by M. Meliner in France in 1865, the chips
from spruce and poplar logs are boiled under pressure in a strong
solution of caustic soda.
When sulphite wood pulp is to be prepared, the chips are conveyed from
the chipper into hoppers in the upper part of the building. Here they
are thrown into great upright iron boilers or digesters charged with
lime-water and fed with the fumes of sulphur which is burned for the
purpose in a furnace adjoining the building and which thus forms acid
sulphide of lime. The sulphite process was originally invented by a
celebrated Philadelphia chemist, but was perfected in Europe.
The "cooking," or boiling, to which the wood is subjected in both the
soda and sulphite processes, effects a complete separation of all
resinous and foreign substances from the fine and true cell tissue, or
cellulose, which is left a pure fiber, ready for use as described. In
the case of all fibers, whether rag or wood, painstaking work counts,
and the excellence of the paper is largely dependent upon the time and
care given to the reduction of the pulp from the original raw material.
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