38 BULLETIN 343, U. S. DEPARTMENT OF AGRICULTURE. 
spruce. All the substitutes, however, with the possible exception | 
of noble fir and amabilis fir, required the use of more power per ton | 
of pulp. Also, while a good grade of spruce | 
pulp can be produced under widely varying | 
conditions of grinding, the best results were | 
generally obtained from the other woods when | 
the stone was somewhat dull, the pressure high, | 
and the speed of grinding rather slow. 
THE FIRS. 
The firs tested were balsam fir (Abies bal- 
samea), red fir (Abies magnifica), white fir (Abies | 
concolor), amabilis fir (Abies amabilis), alpine | 
fir (Abies lasiocarpa), lowland or grand fir | 
| (Abies grandis), and noble fir (Abies nobilis). | 
Fic. 24—Red fir (Abies mag. | A good sheet of pulp can easily be obtained 
Tee from balsam fir if the wood is in a green state. 
Such pulp is as light m color as, if not lighter than, spruce, and a | 
fairly sharp stone can be used in grinding it. Seasoned wood, how- | 
ever, usually shows | 
decay and insect at- 
tack, and it is prac- 
tically impossible to 
grind it into pulp 
which will not contain 
many shives and be 
somewhat soft. The 
yield from balsam fir 
is about 1,910 pounds 
(bone-dry pulp) per 
hundred cubic feet of 
solid rossed wood, or 
approximately 490 
pounds less than the 
yield from an equal 
quantity of white 
spruce. . 
Red fir, like balsam, 
is easily ground to a 
pulp satisfactory for 
news-print purposes. 
It required, however, 
more power per ton of pulp, due possibly to the fact that the wood | 
used in the experiments was of such a large diameter that it had to — 
Fig. 25.—White fir (A bies concolor). 
