12 BULLETIN" 475, U. S. DEPARTMENT OF AGRICULTURE. 



usually so open at the bottom that it is not necessary to make special 

 provision for fresh air. Where the drying room is heated from 

 below fresh air can be admitted through dampers or ventilators in 

 the jacket surrounding the stove. Vents to maintain circulation 

 should also be provided in the roof of the drying room. 



Though they are usually the best that are practicable, these methods 

 of ventilation are necessarily crude and wasteful. As the air cools 

 and absorbs moisture it becomes heavier and sinks to the floor. Vents 

 in the roof carry off much of the hot, dry, light air which should be 

 retained. A certain amount of heavy, moist air is, however, carried 

 out with 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 cones. 

 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 having inlets at the floor level and 

 passing through the roof. 



WETTING CONES. 



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 un- 

 moistened 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 that it 

 loosens 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 fertility 

 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 in- 

 jured the seed. As a general rule, the cones should be as dry as 

 possible before they are put into the kiln. Preliminary drying in 

 the open or in well-ventilated storerooms will hasten opening after 

 artificial heat is applied. 



