CONTROL OF DECAY IN PULP AND PULP WOOD 49 
In some cases the amount of chemical recommended above is less 
than that indicated in Table 13 as the effective quantity, but it 
should be borne in mind that there was a much greater loss of chemical 
from diffusion in the laboratory tests than would obtain in industrial 
practice. 
In order to gain some idea of what additional expense the mills 
would consider practical for safeguarding pulp to be stored for any 
considerable time, a number of questionnaires were sent out in May, 
1921. Twenty-three replies were received. The estimates of the 
nine companies submitting definite figures varied from SI. 25 to S6 
per ton, the average for maximum figures being about $3.50. On 
this basis only three of the preservatives suggested herein would be 
available, namely, cymene-naphthalene mixture, sodium dinitro- 
phenolate, and sodium dichromate; but improved methods of apply- 
ing the preservatives, so that a greater amount will be retained by 
the pulp, may hereafter permit the use of lower concentrations and 
thus make possible the use of some of the more expensive chemicals. 
SUMMARY 
An extensive survey of storage conditions at pulp and paper mills 
indicates that serious losses occur both in stored wood and in pulp, 
especially ground wood. Storage conditions in the woods and at 
the mill can be improved so as to reduce these losses. 
The deterioration of wood and wood pulp is due mainly to fungi. 
For practical purposes these fungi may be divided into two general 
groups — molds and wood-destroying organisms. The former dis- 
color the pulp but do not appreciably affect its strength; the latter 
produce true decay. 
The character of the wood available for puloing is an important 
factor in its storage. Pulp wood usually consists of the less dur- 
able species. The length of storage, the time of cutting, the removal 
of bark, the presence of insects, methods of piling, and general sani- 
tation about the yards are all conditions which affect the life of wood. 
The prevailing methods of storing wood are discussed in detail, and 
the desirability of segregating infected from sound wood and of 
pulping all wood in rotation is emphasized. 
In order to demonstrate the difficulties met with and the large 
losses sustained in the use of decayed wood, a considerable amount 
of wood in various stages of decay was pulped by the mechanical, 
sulphite, and soda processes. The grinder runs on (spruce) wood 
which had been stored for three years under unfavorable conditions 
demonstrated a loss in yield of 16 per cent, based on weight of oven- 
dry barked wood. The resulting pulp was freer, contained a larger 
number of shives, and was decidedly darker in color than pulp 
made from sound wood. In the manufacture of chemical pulps, 
chipping losses ranged as high as 17 per cent for badly decayed 
material as compared with 4.4 per cent for sound material. The 
Note.— Final conclusions as to the value of decayed wood, in general, for chemical pulp should not be 
drawn from the specific data presented in this bulletin. The value of decayed wood for sulphite pulp is 
closely associated with the chemical action of the wood-destroying organisms, and these organisms vary 
widely in their method of attack. Further investigations, under way at the Forest Products Labora- 
tory, indicate already that some types of rot tend to reduce the value of wood for sulphite pulp less than 
the* superficial appearance of the wood might suggest. 
523°— 25f 4 
