12 EXTRACTING AND CLEANING FOREST TREE SEED. 



DISTRIBUTION OF HEAT. 



One of the most difficult problems in running an improvised kiln 

 is to maintain a constant supply of heat and distribute it evenly 

 through all parts of the drying room. The first step should be to 

 make the room, whether in a building or tent, as tight as possible, 

 except for the vents required for ventilation. All chinks in a build- 

 ing should be closed completely. The next precaution is to secure 

 as constant temperature as possible. Wherever practicable, as hot 

 a fire should be kept up at night as during the day. This is particu- 

 larly necessary in a tent, where any dying down of the fire at night 

 causes the air to cool rapidly, with consequent delay and loss of time 

 and labor. 



The stove has ordinarily been placed in the center of the room 

 and approximately level with the lowest tiers of trays. This results 

 in much slower drying of the cones near the bottom of the room 

 and at a distance from the stove. Attempts have been made to 

 obviate this difficulty by dividing the stovepipe into sections and 

 carrying it through as much of the room as possible, but without 

 complete success. Better drying is secured in the farther ends of 

 the room, but the bottom remains much cooler than the top. This 

 difference is especially marked in tents, where cold air constantly 

 passes in under the walls. With only one stove, even distribution 

 of heat is impossible. With stoves set at opposite ends of the tent 

 and connected by a single stovepipe, conditions are but little better. 

 In one instance where this arrangement was used, a difference of 

 from 20 to 30 F. was found in the temperature of the air at the 

 highest and lowest trays in a six-tier stack 



One method of hastening the opening of the cones in the lower 

 trays is to raise them as the drying proceeds and the cones in the 

 upper trays are removed. This, however, requires additional hand- 

 ling and loss of time. A better method wherever space is available 

 is to place the lowest tier of trays somewhat above the stove. Room 

 for air circulation is essential. The tiers of trays should be at least 

 6 inches apart vertically, preferably 8 inches, and the same distance 

 from the walls. 



Heating the dry room from below, The best method of securing 

 even distribution of heat, although not always practicable, is to have 

 the drying room heated from below. If conditions permit, excavate 

 under the building and place the stove below the floor. This will 

 mot only heat the room above more evenly, but furnishes additional 

 space for spreading cones. The stovepipes should pass through as 

 many parts of the dry room as possible. Still better results will be 

 obtained if hot-air pipes can be conducted from the drum of the 

 stove into the room above, and even more heat can be made available 



