28 BULLETIN 343, U. S. DEPARTMENT OF AGRICULTURE. 
The rate of growth seems to have little effect upon the power 
consumption or rate of production. When the wood is of large 
diameter it is necessary to split a considerable portion of it and more 
or less binding is caused, this resulting in a higher power consump- 
tion per ton of pulp. The yield and quality are both slightly in- 
fluenced by the rate of growth of the wood. The yield is lower from 
wood of rapid growth than from wood which has grown slowly. The 
pulp is softer when rapid-growth wood is used, although the strength 
is practically the same. Generally woods which are highly lignified 
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BESS EA Eleeasistills 
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REVOLUTIONS PER MINUTE 
td GH Ga ee. 
geal 
‘PRESSURE OM 14 INCH CYLINDER — POUNDS PER 3Q. IN. 
Sea eCe Rees BSE ae Ueeee 
40 100 120 150 250, 300 400 Oh = a ee 
HORSEPOWER on ‘tom [BONE RY] HORSEPOWER TO GRINDER TONS [BONE DRY] IN 24 HOURS 
Fig. 18.—Relation of power consumption and production to pressure and speed—horsepower to grinder 
constant. (Tamarack runs 62 to 68, inclusive.) 
yield shorter fibered pulps than those having large amounts of 
sapwood. 
The conditioa of the wood as regards decay has a marked effect on 
the pulp. With the use of partially decayed wood the yield of pulp — 
from a cord is greatly decreased, and while the wood grinds faster 
than entirely sound wood, giving an increased production and a cor- 
respondingly lower power consumption per ton of pulp, the pulp © 
consists principally of extremely short fibers and wood flour, which 
greatly decrease its strength. (Spruce runs 255 and 256.) At the 
same time the color is materially darker than that of the pulp pro- 
duced from sound wood. 
