Pulp and paper magazine of Canada . and the speeds were, respectively100, 150, and 200 revolutions per minutefor the hemlock, and 152 and 205 revo-lutions for the jack pine. There is littledifference in the fibres ground under these which these results were obtained are con-siderably lower than those ordinarily em-ployed commercially, and the results havelittle significance. If the stone is what isordinarily called sharp, it is necessary touse a lower pressure, and when dull, ahigher one, but it is impossible to obtainthe same quality of pulp under both con-ditions. Speed and pressure affect q
Pulp and paper magazine of Canada . and the speeds were, respectively100, 150, and 200 revolutions per minutefor the hemlock, and 152 and 205 revo-lutions for the jack pine. There is littledifference in the fibres ground under these which these results were obtained are con-siderably lower than those ordinarily em-ployed commercially, and the results havelittle significance. If the stone is what isordinarily called sharp, it is necessary touse a lower pressure, and when dull, ahigher one, but it is impossible to obtainthe same quality of pulp under both con-ditions. Speed and pressure affect quan-tity rather than quality, and by the pro-per adjustment of both the maximum effi-ciency of grinding is attained. If a cer-tain speed is selected there must be acorresponding pressure which will yield thegreatest amount of pulp in 24 hours withthe least consumption of power. By the term * constant pressure,whereever used in this report, is meant con-stant pressure on the grinder pressure per square inch of wood in. •% M different conditions of speed; especiallythose run at 150 and 200 revolutions perminute. Speed probably has very littleeffect on the quality of pulp. With satisfactory pressure and surface of stone, itis possible to obtain good grades of pulpat any speeds within reasonable limit?.Commercially, it is practically impossibleto maintain the speed constnnt at alltimes. When the pressure on a pocket isremoved the speed is bound to rise eoji-siderably, especially when the wat(Mwheels or turbines are operated withouta governor. When hemlock wood was ground at lowspeed and low pressure it was impossibleto obtain anything more than a when this wood was ground at lowpressure and high speed the product wasextremely short, but the pressures at contact with the grinding surface variesconsiderably, chiefly with the size of woodground and the area of the pocket. Again,the length of the wood is not at all aconstant quantity, and this, too, can only
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