996 JOURNAL OF FORESTRY 



About two-thirds of the cones opened wide with 35 per cent to 39 per 

 cent of the green weight lost, four-fifths of them when 40 per cent to 

 48 per cent was lost, and all of them when 51 per cent was evaporated. 



(b) Relation between per cent of weight lost by cones and per cent 

 of germination of seed. — In a kiln treatment it usually is not feasible 

 to remove any of the seed until the drying is finished. In this event 

 there arises a question as to the severity of drying : Is it better to con- 

 tinue the treatment until all cones are open, or will such prolonged dry- 

 ing injure the quality of the seed? In this connection the following 

 results are illuminating: When 35 per cent to 39 per cent of the cone 

 weight was lost, the germination of the seed was 28 per cent ; when 40 

 per cent to 44 per cent was lost, the germination was reduced to 18^ 

 per cent; and with 51 per cent lost, only 2 per cent of the seed germi- 

 nated. (All germination figures are low because the seed was not 

 cleaned, and much hollow and wormy seed was therefore sown in the 

 tests.) It is very evident that prolonged drying is disastrous, and that 

 the treatment should be shortened even to the point of wasting such 

 cones as do not open readily. Probably not over 40 per cent of the 

 green weight of cones should be evaporated, if the seed can be removed 

 only when the drying is finished. 



{c) Factors which influence cone drying. — Table 4, which sum- 

 marizes the main results of the cone-drying tests, is arranged according 

 to the degree of drying, as indicated by the per cent of weight lost by 

 the cones. A casual examination of the table shows that drying is the 

 complex result of temperature, humidity, and air circulation. 



Other things being equal, it is of course certain that the rapidity of 

 drying will be proportionate to the temperature maintained. With low 

 humidity and fair circulation, a temperature of 70° F. caused a loss of 

 II per cent to 16 per cent of weight in nine hours, while one of 100° F. 

 for the same period caused a loss of 35 per cent to 44 per cent ; a tem- 

 perature of 80° F. for 19!/^ hours caused the same loss as one of 120° F. 

 for 6^ hours — 39 per cent. 



It is likewise certain that drying progresses at a rate proportionate to 

 the relative humidity, other things being equal. At a temperature of 

 100° F. and with slight circulation of air, a relative humidity of 70 

 per cent was accompanied by a loss of 19 per cent, as contrasted with 

 2y per cent when the humidity was 40 per cent. At 130° F. a relative 

 humidity of 56 per cent resulted in only 19 per cent loss, while one of 

 16 per cent caused 39 per cent loss. 



The result of air circulation is shown by the fact that at 120° F. a 

 slight circulation (humidity 17 per cent) caused a loss of 34 per cent, 



