22 



BULLETIN 343, U. S. DEPARTMENT OP AGRICULTURE. 



The effect of pressure on the quality of pulp as indicated by the 

 strength of paper made from it is shown in figure 13. The strength 

 factor, or bursting strength per square inch divided by the weight per 

 ream, decreased with increasing pressure. The decrease in power 

 consumption per ton is also shown. 



PERIPHERAL SPEED OF STONE. 



In figure 14 is shown the variation of the horsepower consumption 

 per ton, horsepower to the grinder, and production in 24 hours, with 



2000 2100~~ 2200 2300 



YIELD PER 100 CU.FT.0F SOLID R0SSED W00D-LBS. 



Fig. 12.— Relation of yield to pressure. (Spruce runs 52 to 56, inclusive.) 



varying speed of pulp stone. The decrease in the power consumption 

 per ton from 100 to 250 revolutions per minute when steamed wood 

 is used is much greater than when unsteamed wood is ground under 

 the same conditions. (See fig. 15.) 



The pressure at which wood is steamed prior to grinding has a 

 marked influence on the speed of rotation of the pulp stone necessary 

 to consume a certain amount of power when the grinding pressure is 

 maintained constant. This is shown in figure 16. The wood was 



