SEED-KILNS. 681 



The advantages of steam drying over hot air drying are, as 

 follows : 



There is no fear of a conflagration in the seed-kiln ; by 

 means of in and out draughts, heat can he supplied according 

 to requirements, and the amount necessary for opening the 

 cones is attained in one-quarter of the time required by the 

 hot air apparatus, whilst the whole time occupied by the 

 process is shortened by one-quarter ; the temperature cannot 

 exceed 133 F., so that there is no danger of over-heating the 

 seed. Keller's process gives from 87 to 97 per cent, of 

 germinating seeds, which, according to Braun, are not only 

 considerably superior in germinative power to seeds from hot 

 air kilns, but also can be kept longer. 



4. Management of Seed-husking Works. 



The system followed in the different seed-husking estab- 

 lishments is of a simple nature. The cones from the store- 

 house are placed in sacks or otherwise brought to the seed- 

 kiln and placed on the trays. After the heat has been applied 

 and the cones begin to steam, all vent-holes must be opened. 

 As soon as the air becomes drier and the cones have been 

 exposed for some time to the heat, they begin to open. Gene- 

 rally this does not happen simultaneously on all the trays ; 

 the current of hot air is then turned in the direction of the 

 backward trays by opening certain vent-holes, or changing the 

 places of those trays with those where the cones have opened 

 and thus exposing them to the hottest blast. 



Management of the heat is the most important point in the 

 kilns. The heat should rise as uniformly and quickly as 

 possible to the temperature most suitable for the apparatus and 

 cone in question. Scots pine cones require the greatest heat, 

 usually 90 to 125 F. ; spruce 80 to 90 F. ; Weymouth-pine 

 and alder, 60 to 70 F. 



In order to guard against over-heating by the workmen, Keller, 

 in Darmstadt, has an electric bell in his office communicating 

 with a metallic maximum thermometer in the kiln. 



The cones on removal from the trays are thrown usually on 

 to a grating so that the seeds may be separated from them ; 



