32 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
If it were commercially feasible always to dry the pulp below the 
limits required for fungous growth, say to from 15 to 20 per cent, 
or, on the other hand, to keep it completely saturated, the problem 
would be largely solved. (See Blair and Parke- Cameron (7) for a 
discussion of under-water storage for mechanical pulp.) 
WORK OF OTHER INVESTIGATORS 
The writers are aware of only one reference in literature to attempts 
earlier than their own to preserve pulp from decay by the addition 
of antiseptics. This is a brief mention by Wolesky (27) of prelimi- 
nary tests, from which he concludes that 0.25 per cent solutions of 
sodium chloride, magnesium sulphate, or aluminum sulphate applied 
on the wet machine would protect ground wood. 
Concurrently with the present investigation, Bates (3) has discussed 
tests made at the Kenogami mill of Price Brothers & Co. (Ltd.), 
of Canada. This investigator reports spraying approximately 29 
tons of wet pulp with three chemicals— zinc chloride, mercuric chlo- 
ride, and sodium fluoride. The chemicals were applied as a water 
solution by means of a perforated brass pipe, which delivered about 
5 pounds of solution per minute on a felt roll fitted to the top press 
roll. Zinc chloride was used in a 3 and a 7.15 per cent concentration, 
mercuric chloride in a 0.107 and a 0.428 per cent solution, and sodium 
fluoride in a 1.14 and a 2.S6 per cent solution. Some solution was 
necessarily pressed out and lost in the white water. 
After treatment most of the material was piled in a storage shed. 
For the first eight months it lay in separate exposed piles at one end 
of the building, in a cool location, and showed little change. Later 
the pilei were transferred to the middle of the building and buried 
under the § bison's supply of pulp. After 12 months they were again 
inspected. In no case, even in the adjacent untreated pulp, was 
deterioration serious. 
At the time the material was put into the storage shed about 20 
laps treated with each preservative, together with 20 untreated laps 
for each, were placed in a closed, humid kiln of brick construction 
in the mill basement, where conditions for decay were very much 
more favorable. After 18 months this material was in a condition 
far different from that of the material placed in the shed. The laps 
with the light and the heavy zinc chloride treatments were badly discol- 
ored by black fungous spots scattered throughout the pulp, the effect 
being worse in the case of the heavier chemical treatment. Those 
treated with mercuric chloride, both light and heavy, were also badly 
discolored with green and gray mold patches, although the pulp was 
fairly well preserved from decay. Those from the sodium fluoride 
solution, however, were in strikingly good condition as compared with 
the untreated pulp, which was seriously molded and rotted. These 
tests pointed to the conclusion that sodium fluoride in 1.14 per cent 
concentration, applied at the rate of about 12 pounds per ton of air- 
dry pulp, or 4 pounds per ton of wet pulp having a moisture content 
of 72.7 per cent, probably may be used very effectively as a preserva- 
tive for ground wood. 
