THE SUITABILITY OF AMEBIC AN WOODS FOB PAPEB PULP 23 
opportunity has offered to carry on cooks in the mill under similar 
conditions, similar results have been obtained. Nevertheless there 
is always the possibility of divergence on account of the larger 
volumes of commercial cooks and the greater ratio of volume of 
digester to surface. 
In estimating the pulping characteristics of the various woods, it 
has necessarily been assumed that the mill operator will take advan- 
tage of the best information available as to methods of operation. 
Due consideration has been given, however, to variations and 
irregularities of mill conditions, which militate against the highest 
yields and quality of pulp. 
APPLICATION OF DATA TO OPERATING CONDITIONS 
The oven-dry weight of the wood per cubic foot, green volume, 
given in the summaries, may be used as a factor in converting pulp 
yield by weight to yield per cord or any other unit of volume. Yields 
per cord may be determined by multiplying the yield of pulp based 
on weight by the oven-dry weight of the wood per cubic foot, and 
the product by the number of cubic feet solid wood obtained from a 
cord — due attention being given the character of the wood available 
from the particular species. The yields of pulp to be expected per 
cord or per thousand board feet are not directly stated as such 
because it was thought advisable that the reader excercise his own 
judgment in interpreting the data in this respect. The volume of 
solid wood per cord is an uncertain figure, which may vary from as 
little as 50 up to 100 cubic feet, according to the kind, shape, dimen- 
sions, soundness, and mechanical condition of the material. Rossed 
2-foot spruce bolts of mixed diameters ranging from 6 to 14 inches 
contain slightly over 100 cubic feet per cord, and 100 cubic feet is 
assumed in figuring yields. Four-foot rossed bolts run 2 to 3 per 
cent less, 4-foot peeled bolts about 7 per cent less, and 4-foot rough 
bolts from 20 to 25 per cent less. The solid cubical content of mill 
waste varies enormously. Frequently 2 cords of mill waste will 
be found to yield only as much solid wood as 1 cord of 4-foot round 
bolts with the bark on. 
The yield of oven-dry pulp is given in percentage of the oven-dry 
weight of the chips. Yields of less than 40 per cent are, in general, 
too low for profitable production, especially from woods lighter than 
22 or 23 pounds to the cubic foot. Bleachability, discussed later, 
is a factor entering into calculations in this connection. 
The physical characteristics of the species under consideration 
are not dwelt upon, such information being readily available in 
various works on forestry and on properties and uses of wood. They 
are, however, of especial importance in so far as they affect the ease 
with which the wood may be chipped and the bark removed; many 
species which may be easily pulped are rejected on account of the 
difficulty in handling them in the wood room. 
In considering the suitability of a species in a given locality for 
pulp-making purposes, account should be taken of its growth habits, 
since the same species often varies greatly in properties with the 
latitude, altitude, character of soil, and other conditions of its environ- 
ment. 
Neither the durability of a species (i. e., resistance to decay) 
nor its susceptibility to insect attack is covered in this report, although 
