10 BULLETIN 152, U. S. DEPARTMENT OF AGRICULTURE. 
PULP. 
In 1905 hemlock formed 11.8 per cent of all the wood used for 
pulp. In 1906 and 1907 it supplied 14 per cent of the total amount; 
in 1908, 17 per cent; in 1909, 14 per cent; and in 1910, 15 per cent. 
During the latter year its consumption was 50 per cent greater than 
in 1905. 
Hemlock pulp is used for news, wrapping, and other cheap grades 
of paper, and is manufactured chiefly by the sulphite process. In 
this process the wood is first chipped and then cooked in a solution 
of calcium sulphite, which frees the fibers by dissolving the sub- 
stances that unite them. The dissolved substances comprise about 
half the original weight of the dry wood, without bark. Hemlock 
also furnishes a small amount of ground wood pulp, but the great 
bulk of this is spruce. Ground wood is inferior to chemical pulp, 
since the fibers become broken in grinding, while the pulp contains 
the useless constituents which are dissolved out in the chemical 
process. As a result it is mealy and less interlaceable, especially in 
the case of hemlock, the fibers of which are shorter than those of 
spruce. In spite of this, a very serviceable grade of news paper can 
be made from hemlock pulp, 75 per cent ground and 25 per cent sul- 
phite, with almost the strength, finish, and appearance of that made 
chiefly of spruce. 1 
Since the value per ton of ground wood is only about $15, as com- 
pared with $47 for sulphite pulp, the former is used as the basis for 
news and other cheap grades of paper, to which a small amount 2 of 
sulphite pulp is added for strength. Spruce once furnished prac- 
tically all of both kinds of pulp, and still supplies 90 per cent of the 
mechanical pulp. Its increasing cost has brought about the use of 
cheaper woods in the sulphite process, during which so much of the 
volume is lost. Spruce now supplies less than 60 per cent of the sul- 
phite pulp, while hemlock supplies about 25 per cent. The propor- 
tions of hemlock manufactured by the various processes for the six 
years from 1905 to 1910, inclusive, were — 
Per cent. 
Sulphite process 94. 75 
Mechanical process 4. 5 
Soda process 7 
Sulphate process .05 
100. 00 
Hemlock pulpwood is marketed both as cordwood and in the log. 
In Wisconsin pieces 8 inches and over at the small end are ordinarily 
cut in log lengths and sold by the thousand board feet, 1,000 
board feet usually being considered equivalent to 2 cords. Pieces 
i J. H. Thickens: "Experiments with Jack Pine and Hemlock for Mechanical Pulp." Dept. of Agri- 
culture, Forest Service Forest Products Laboratory Series, June 11, 1912. 
*The usual proportion is from 70 to 84 per cent ground pulp to from 16 to 30 per cent sulphite. 
