Pulp and paper magazine of Canada . must be exercised ingrinding them. It is possible to obtain agrade of pulp from spruce which is suit-able for most purposes without using agreat deal of care in the preparation of the were the variables which received most at-tention. No especial attention was given toeconomic considerations. Tests were made with pressures of from20 to 75 pounds per square inch on thecylinder, corresponding to from to per square inch of pocket area. Thespeed of rotation of the stone was variedfrom 84 to 225 revolutions per minute, cor-responding to a range in
Pulp and paper magazine of Canada . must be exercised ingrinding them. It is possible to obtain agrade of pulp from spruce which is suit-able for most purposes without using agreat deal of care in the preparation of the were the variables which received most at-tention. No especial attention was given toeconomic considerations. Tests were made with pressures of from20 to 75 pounds per square inch on thecylinder, corresponding to from to per square inch of pocket area. Thespeed of rotation of the stone was variedfrom 84 to 225 revolutions per minute, cor-responding to a range in peripheral speedof from 1,173 to 3,150 feet per minute. In studying the effect of the surface con-dition of the stone it was necessary to uti-lize burrs of many different types and de-signs. These ranged in fineness of cut from12 to the inch to 3 to the inch. The styleof cut differed also, spiral cut, diamondpoints, and straight cut being employed. Thepower applied to the grinder ranged to 520 horsepower, while the rate of. surface of the pulp stones. lu tlie grind-ing of jack pine and hemlock, especiallyhemlock, on the other hand, great care mustbe exercised in bringing the stone to thecorrect degree of sharpness, since thesewoods will grind to powder if the surfaceis as sharp as the one ordinarily employedin grinding spruce. Yet notwithstanding certain shortcomingsthe fact remains that it is possible to obtainhemlock and jack pine pulps commerciallywhich are suitable for the cheaper gradesof paper. Qualitative nd Quantitative order to cover the field in a reason-able length of time, short tests ranging upto two hours in length were run. In thesetests no attempt was made to cover everypoint, the object being to touch only suchas were thought to have a marked effect onthe quality of the product. The surface ofthe stone, the pressure on the grinder cylin-der, and the peripheral speed of the stone production of bone-dry pulp \aried from 1ton to tons in 24 ho
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectpaperma, bookyear1903
