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 ne^r 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- 

 tility 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 

 yielded 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. 



TEMPERATURE 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 



