FIFTEENTH ANNUAL YEAR BOOK — PART VIII. 515 



THE SOUECE OF MOISTURE IN THE HIVE. 



All northern beekeepers know that under some conditions, especially 

 in the cellar, the atmosphere in the hive in winter may become so laden 

 with moisture that it cannot all remain in the form of water vapor but 

 condenses on the hive and combs. Water may even run from the hive 

 during the winter confinement. Obviously this moisture does not come 

 from outside the hive for this often occurs when the cellar appears dry. 



Within the hive the only source of moisture is the food consumed by 

 the bees. Honey not only contains about 20 per cent water but when the 

 sugars are consumed and assimilated the final products are carbon dioxide 

 and water. Honeys vary in composition but on an average when one pound 

 of honey is consumed there is produced about two-thirds of a pound of 

 water, and since honey is one and one-half times as heavy as water, one 

 gallon of honey when consumed produces approximately one gallon of 

 water. 



If we take for example a bee cellar containing 216 colonies and estimate 

 the average consumption of honey during the winter at ten pounds per 

 colony the total honey consumed is 2,160 pounds or 180 gallons. This pro- 

 duces 1,440 pounds of water or 180 gallons, enough to fill six 30 gallon 

 barrels. If these colonies are in the cellar for four months there will be 

 given off one and one-half gallons of water a day and unless there is con- 

 siderable movement of air within the cellar the atmosphere cannot take 

 it all up as water vapor and condensation will occur. 



THE EELATIOX OF HUMIDITY TO TEMPEEATURE. 



Before discussing the changes which take place in the humidity of 

 the hive it may be best to take up some facts concerning the moisture 

 content of the atmosphere as influenced by temperature. It is of course 

 well known that if warm moisture laden atmosphere is cooled its capacity 

 for water vapor is decreased and moisture is condensed. This is shown 

 in the condensation of moisture on the outside of a glass of ice water. 

 Similarly we have condensation on the surface of the leaves which we 

 call "dew" if the moisture remains liquid and "frost" if it is frozen as it 

 condenses. These phenomena are duplicated in the bee hive and bee 

 cellar. 



The problem of the beekeeper is to eliminate this moisture, which leaves 

 the body of the bee in the form of water vapor, without condensation. 

 This has been done in cellar wintering (1) by raising the temperature 

 of the outer air, (2) by drying the air (as by the use of unslaked lime 

 in the cellar) or (3) by causing the air to move so that as the atmosphere 

 becomes laden with moisture it is replaced with other air capable of 

 taking up more moisture. 



To determine by weight the actual amount of water in the atmosphere 

 is difficult in ordinary practice and the usual method is to determine the 

 relative humidity, that is the amount of moisture in the atmosphere com- 

 pared with the maximum which might be held at that temperature. The 

 common method is by the use of the wet and dry bulb thermometers, to 



