GROUND-WOOD PULP. AD5 
Through a mistake in shipment a quantity of white pme (Pinus 
strobus) was received at the laboratory. . It had not been the inten- 
tion to test this wood, since its value for lumber eliminates it from 
consideration as a possible substitute for spruce. Tests were made 
on it, however, since it was at hand. It can be ground on a fairly 
sharp stone to yield fibers of good strength and excellent color. The 
pulp contains a considerable amount of pitch, and, like that from the 
other pines, is inclined to be soft. The yield was approximately 
1,885 pounds per hundred cubic feet of solid rossed wood. 
THE SPRUCES. 
Engelmann spruce (Picea engelmanni) can be ground under the 
same conditions used for white spruce. The pulp has an excellent 
color and a long strong fiber. The fact that the wood ground at 
the laboratory was in a green state undoubtedly made it easier to 
produce a good grade of pulp. Wood 
obtained from Colorado in the form of 
small logs showed no difference in quality 
from similar material obtamed from Mon- 
tana, though the latter, owing to its 
greater weight per cubic foot, yielded 
about 2,250 pounds of pulp (bone dry) 
per hundred cubic feet of rossed wood 
against 2,000 pounds for the Colorado 
material. 
Sitka spruce (Picea sitchensis) yields a 
pulp of very good quality, though not — Fe. 33.—Western larch (Larix occi- 
equaltothatfromwhitespruce. Although ee) 
the wood can be ground under practically any condition of speed, 
sharpness of stone, and grinder pressure, the fibers are not as fine 
-and long as those of the white spruce. In color, moreover, Sitka 
spruce pulp is inclined to be grayish. The wood tested was cut during 
the latter part of April and contained considerable pitch. It undoubt- 
edly would have run better had it been cut earlier in the year. The 
yield was 2,100 pounds per hundred cubic feet of solid rossed wood, or 
about 200 pounds less than that from an equal amount of white 
spruce. 
THE HARDWOODS. 
Aspen (Populus tremuloides) requires the consumption of a large 
amount of power to produce pulp which will run satisfactorily on the 
wct machine. If the pulp stone is too sharp or a less amount of 
power is used, the pulp will be very short. When mixed with spruce, 
however, it operates very satisfactorily. Aspen pulp possesses good 
