Timbers. 



94 



[Feb. 1907. 



according to the chemical solvent employed in the manufacture — we have sulphite 

 wood fibre, soda fibre, and sulphate fibre, or pulp prepared by the action of sulphate 

 of lime, caustic soda, and a solution of sulphates of soda, respectively. 



WOOD-STUFF, OR MECHANICAL WOOD PULP. 



Dr. Joseph Bersch, a well known authority, describes mechanical wood 

 pulp as wood converted be purely mechanical means into a fine fibred mass, which 

 by itself may serve for the production of coarser grades of pasteboards as well as 

 for the manufacture of various articles. Its chief use, however, is an addition to 

 paper stock for the manufacture of inferior grades of paper. Although wood stuff, 

 if properly prepared is sufficiently fine-fibred to be made into paper in the paper 

 machine, it is not used by itself for this purpose, because such paper possesses 

 the undesirable property of becoming darker and acquiring, in a short time, a brown 

 colouration when stored exposed to the light. The cause of this phenomenon is, 

 in Dr. Berschs's opinion, found in the fact that the wook stuff still contains nearly 

 the entire quantity of encrusting substance— lignin, etc.,— originally present in 

 the wood, these substance being subject to great changes. Hence, in the course 

 of time efforts were made to remove these substances from the wood, so that only 

 pure cellulose remains behind, which, as it does not show the already mentioned 

 defects can be used practically by itself for the manufacture of paper. 



WOOD FOR GRINDING. 



Although practically every kind wood may be made use of and put into 

 the grinder, some woods are far preferable to others, and of the European varieties 

 of the wood, ash, linden, fir, pine, and birch are particularly suited for the purpose ; 

 whilst beech may be used, but is considerably less suitable. 



In 1844 there was patented in Germany a machine for grinding wood for 

 the manufacture of pulp. The inventor. Keller, sold the patent to the firm of 

 Henry Voelter's Sons, who afterwards used the pulp in the manufacture of " news " 

 paper. The Voelters made numerous improvements in Keller's invention, and a 

 quarter of a century after it was patented in Germany by Keller, this wood-pulp 

 machine was destined to play an important part in the United States, when, in 

 response to the demand for the rapid printing of daily newspapers, the web press 

 was to come into use. The Voelters— Christian and Henry — made numerous improve- 

 ments in the machine, Christian Voelter obtaining patents in various European 

 countries- in France even as early as April 11th, 1847. Henry Voelter patented 

 his improvement on the pulp machine in Wurtemburg, Germany, on August 29th, 

 1856, and in the United States on August 10th, 1858. 



Various methods of treating wood previous to submitting it to the action 

 of the grinders have been proposed and used. By one process the logs of wood 

 after being cut into suitable lengths for grinding are treated by first steaming them, 

 then removing the acids generated in the steaming operation, next treating the 

 steamed wood with alkali, and, finally, grinding or reducing the pieces to pulp. 

 Steaming has been resorted to for the purpose of removing the bark from wooden 

 blocks preparatory to grinding the solid parts ; and wood has also been treated 

 with water sprinkled on it from above, and steam simultaneously applied from 

 beneath it, in order to soften and cleanse it preparatory to grinding. 



But the process which we shall now describe, which is that of Mr. George F. 

 Cushman, of Barnet, Vermont, is intended to facilitate the disintegration of the 

 fibres, when submitted to the action of the revolving stones by a preliminary cooking 

 of the block of wood in a bath of boiling hot water with lime, soda-ash, or equivalent 

 chemical agent in solution, to soften the block, toughen the fibres, and lessen their 

 lateral adhesion. By this process the block is reduced to pulp with much less power 



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