CONSTRUCTIVE BEEKEEPING 39 



midity outside, give an unequal vapor tention and cause vapor to 

 pass from the outside into the hive. 



When the hive air is cooling it loses some of its moisture 

 which is condensed in the hive. To illustrate ; assume a hive tem- 

 perature of 57 degrees and an absolute humidity of four grains, 

 which temperature is raised to 70 degrees, and still 4 grains of 

 moisture, to equalize the tention of the vapor, inside and outside, 

 some moisture is slowly forced through the opening; let us say 

 until this 70 degree air holds 6 grains. When this air is reduced 

 to 57 degrees and an absolute humidity of 4 grains, two grains of 

 water is left in the hive after this disturbance. 



Suppose the hive is not insulated (no thickness of insolation 

 is too much in any locality whose temperature falls below 50 de- 

 grees) and the outside temperature drops to 32 degrees, the hive 

 temperature drops from 57 degrees, humidity 4 grains, to 40 

 dgrees ; at 40 degrees air is saturated with 2.86 grains. In this 

 case about 1 1-2 grains of water is left in the hive. 



Let us pass to the next cause, the change of the humidity of 

 the outside air. Assume a maximum temperature of 40 degrees, 

 a relative humidity of 84 degrees and an absolute humidity of 

 about 2.30 grains : the hive air at 50 degrees, a relative humidity 

 of 74 per cent and an absolute humidity of 3 grains. To. equalize 

 the tension of the vapor inside and outside the hive a constant 

 movement of vapor into the hive is taking place, which when 

 it is equal to the humidity that the condensing surface of the hive 

 can maintain, is being constantly condensed on the inner surface 

 of the hive. Consider the amount of vapor, that is constantly 

 passing into the hive on days when the relative humidity is 96 

 per cent. There are many days in the more southerly states 

 when a 100 per cent relative humidity obtains. 



Because of the small amount of moisture with which a zero 

 atmosphere is saturated (0.54 grains) bees in the north have 

 less moisture to contend with than in the south, where the tem- 

 perature ranges from 32 degrees up to 60 and 70 degrees. In 

 the latter locality absolute humidity of 32 degree air at satura- 

 tion is 2 grains ; at 60 degrees it is 5.76 grains. In the colder lo- 



