14 EXTRACTING AND CLEANING FOREST TREE SEED. - 
the current, and the circulation of air, so essential to drying the 
cones, is maintained. 
An improved method removes the saturated air directly from 
the floor by pipe ventilators extending from the floor through the 
roof. In one kiln, fresh air is admitted directly under a small box 
stove with a heating drum placed near the center of the room. As | 
this air becomes heated it rises to the ceiling, where it spreads to the 
side walls and, cooling slightly, descends in a steady stream over the 
trays. Each tier of trays is set a little nearer the wall than the one 
above. The trays thus catch the descending current of hot air, which 
flows over them. They are slightly tilted toward the center of the 
room, so that as the air cools and absorbs moisture from the cones 
it runs off the lower edge of the trays like water from a roof. The 
saturated air is sucked up by pipe ventilators passing through the 
roof and having inlets at the floor level. 
APPLICATION OF MOISTURE BEFORE DRYING. 
Wetting cones before drying apparently does more harm than 
good with any species except lodgepole pine. Lodgepole pine cones 
dipped in very hot water for not over one minute have in some cases 
been found to open more readily and to give a higher yield than 
unmoistened cones. This treatment, however, should be applied 
only to very tight cones and should not be of sufficient duration to 
add appreciably to their water content. Its only advantage is in 
loosening the sealed tips of the cone scales. Experiments have also 
shown that live steam applied under a pressure of one-half pound 
for 30 seconds assists in opening cones without impairing the fer- 
iility of the seed. Such treatment, however, is possible only at fully 
equipped extracting plants. 
Even with lodgepole pine, a preliminary wetting is not essential 
and good results are obtained without it. Continued soaking of 
cones has almost uniformly lessened the ease of extraction and 
vielded seed of poorer quality. As a general rule, the cones should 
be as dry as possible before they are put in the kiln. Preliminary 
drying in the open or in well-ventilated storerooms will hasten open- 
ing after artificial heat is applied. 
TEMPERATURD REQUIRED. 
The degree of heat and the length of time required to open cones 
vary somewhat with different species, but still more with the con- 
ditions under which the drying is done. In a well-equipped plant, 
drying may be finished in less than half the time required in a tent, 
even with the same temperature. It is, therefore, impossible to cite 
average figures of general application. Ordinarily, the higher the 
