22 BULLETIN 343, U. S. DEPARTMENT OF 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 — 
PRESSURE ON 14. IN.CYLINDER—LBS.PER SQ.IN, 
2000 2100 2200 2300 
YIELD PER 100 CU.FT.OF SOLID ROSSED WOOD—LBS. 
hi ea ol aa el 
Fig. 12.—Relation of yield to pressure. (Spruceruns 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 
i 
