THE SUITABILITY OF AMEEICAN WOODS FOR PAPER PULP 25 
might not occasionally be obtained by that procedure. It was 
found, however, that the advantages did not hold for sulphite. 
In the soda process, the color of the unbleached pulp is not 
mentioned, since the pulp is almost invariably bleached before using. 
In sulphate pulps from conifers strength is the outstanding require- 
ment, although bleaching qualities are coming into account as the 
use of the bleached product increases. 
With mechanical pulps color is the major consideration and sheet- 
forming qualities are important. Strength is also a desideratum, 
since the stronger the pulp the less sulphite is required to manufac- 
ture paper of specified strength. Many species otherwise suitable 
are not economically feasible for mechanical pulp on account of the 
power required in grinding. Power consumption may therefore be 
the controlling factor. 
The power requirements given in the summaries for the various 
species apply to the production of ground wood of standard strength. 
On account of local conditions it may prove advisable to grind 
coarser or weaker pulps in order to use less power and gain in pro- 
duction and make up for the lower strength of the paper by using 
more sulphite. 
When the establishment of a plant in an area new to the industry 
is in contemplation it is advisable to obtain pulping and paper- 
making tests on representative local samples of the species the use of 
which is intended. It is, of course, obvious that a complete survey 
of the locality should be made to ascertain the amounts of suitable 
species available, their rapidity of growth, the distribution and char- 
acter of stands, etc. There should also be an economic survey of the 
supply of labor, living conditions, freight rates to centers of consump- 
tion, character and quantity of water available, and cost of fuel and 
power. 
SUMMARIES BY SPECIES 
Yields in all cases refer to the oven-dry weight of the pulp and are based on the 
oven-dry weight of the wood. Bleach requirements are expressed as percentages 
of the oven-dry weight of the pulp. 
In the discussion of the coniferous species no mention is made of soda pulp, 
for the reason that strength and susceptibility to bleach, the most important 
qualities of the conifers, are better brought out by the sulphate than by the soda 
process. 
1. THE SPRUCES 
Black Spruce (Picea mariana) 
Other names in use. — Double spruce and spruce pine. In the trade the wood is 
often mixed with red and white spruce and called eastern spruce. 
Range. — Labrador to the MacKenzie River, and northwestward into Alaska; 
southward through Newfoundland, eastern Canada, Michigan, Wisconsin, Minn- 
esota to central Pennsylvania, and in the northeastern mountains to northern 
Virginia. 
Oven-dry weight per cubic foot, green volume. — 23 pounds. 
Fiber length. — 2.6 mm. 
By Sulphite Process 
Reduces readily. 
Unbleached pulp: Strong, of fine texture and excellent color, although occa- 
sionally somewhat pitchy; bleached easily to excellent white. 
Yields: 45 to 50 per cent. 
Bleach required: 10 to 20 per cent. 
Uses to which pulp is suited: News, wrapping, dook, high-grade printing, and 
bond paper. 
