BULLETIN OF THE 
C 
No. 80 
Contribution from the Forest Service, Henry S. Graves, Forester. 
August 31, 1914. 
(PROFESSIONAL PAPER.) 
EFFECTS OF VARYING CERTAIN COOKING CONDI- 
TIONS IN PRODUCING SODA PULP FROM ASPEN. 
By Henry E. Surface, 
Engineer in Forest Products, Forest Products Laboratory. 
PURPOSE OF EXPERIMENTS. 
At the present time practically all of the soft, easy-bleaching pulps 
used for the manufacture of high-class book, magazine, general print- 
ing, and the cheaper writing papers are made by the soda process. 
In England such pulps are produced from esparto (alfa, or Spanish 
grass) ; in America, from the poplars and similar woods. Although 
the soda process of wood-pulp manufacture is not employed commer- 
cially to so great an extent in America as the sulphite and mechan- 
ical processes, it is remarkably well adapted for producing pulp fibers 
from any kind of wood or other fibrous vegetable material, no matter 
how resistant to chemical attack it may be. For this reason it is 
much used in the experimental work of the Forest Service. 
To insure that a wood has been subjected to the most favorable 
cooking conditions it is necessary to cook it under many different 
conditions produced by varying such factors as the amount and con- 
centration of the cooking chemical and the duration and temperature 
of cooking. While the general effect of using greater or less severity 
of cooking is well recognized in mill practice, there has been almost 
no available information on the quantitative effects of the individual 
factors concerned nor on the limitations within which such effects 
are exerted. Such meager information as may be found in the litera- 
ture is widely scattered and is not strictly applicable to manufactur- 
ing conditions. Notwithstanding modern improvements and the 
general tendency toward more efficient operations in commercial 
plants, the most economical production apparently is not being 
attained by all of the soda-pulp mills. This is indicated by the fact 
that some of them are using from 10 to 20 per cent more pulp wood, 
from 50 to 100 per cent more chemicals, and from 10 to 40 per cent 
1 This paper presents detailed information of value in experimental work in the laboratory and in pro- 
moting the efficiency of commercial paper-making plants employing the soda process. 
31091°— Bull. 80—14 1 
