36 BULLETIN 1208, U. S. DEPARTMENT OF AGRICULTURE 
Quantitative analyses of laps from the first set were made after 
two weeks and again after two months. The treated pulp at the 
beginning of the experiment contained 1.16 pounds of salt per 100 
pounds of wet pulp. At the end of two weeks salt from the upper- 
most treated bundle, after an upward penetration of 20 thicknesses, 
showed a concentration of 0.04 pound per 100 pounds of wet pulp; 
from the lowest treated bundle, downward diffusion had evidently 
reached the bottom (through 60 thicknesses), where a concentration 
of 0.01 pound per 100 pounds was indicated. 
In two months the upward diffusion from the first treated bundle 
exceeded 33 laps, concentration reaching 0.03 pound per 100 pounds 
in the thirty-third. In the sixth lap from the bottom of the pile the 
concentration was 0.08 pound per 100 pounds. 
In the drier pulp of the second test set, observations showed that 
diffusion was going on with a rapidity about equal to that in the first. 
No formal record was kept. 
During the storage phase of the preservative experiments at the 
Forest Products Laboratory, diffusion undoubtedly accounted for a 
certain amount of mingling of chemicals as well as loss by penetration 
into untreated spacer laps, and the lower the laps were in the pile the 
greater the diffusion, owing to the greater pressure and closer con- 
tact of the bundles or layers. In the second mill test, however, dif- 
fusion did not affect the results, since pulps of different treatment 
were placed in separate piles. 
As a matter of preservation, the rapid diffusion of a chemical 
through pulp is highly beneficial. From the facts observed it seems 
perfectly safe to conclude that any minor irregularity in the applica- 
tion of the antiseptic is quickly compensated for, and that uniformity 
of treatment is insured. Under manufacturing conditions in which 
every lap in the pile would be treated, loss from diffusion would not 
occur: and, therefore, smaller amounts of chemical than were found 
effective in the laboratory tests can be recommended for commercial 
practice. 
RESULTS OF PRESERVATIVE TREATMENTS 
Table 13 presents a record of preservative treatments applied both 
at the laboratory and at the mills. In its interpretation the foot- 
notes will help to explain certain apparent discrepancies. The results 
of the mill tests, which followed commercial methods, must be the 
final check on the value of the antiseptic. 
In each series of tests a number of untreated laps were interspersed 
in the piles to serve as checks. Their condition was noted at different 
inspections. Except in a few cases where the laps dried too much, 
the records indicate that these check laps were severely or completely 
molded and decayed at the time of the last inspection. 
