-3- 



IS YOIJR STORAGE TOO DRY? 



A dry apple box will absorb as much as a pound of water. If water is not 

 available in the surrounding air, it will be pulled out of the apples in the box. 

 No wonder many apples become wrinkled in storage, and also that growers are showing 

 increasing interest in a method of measuring Relative Humidity. The wet and dry 

 bulb thermometer, sometimes called a sling psychrometer, has become standard equip- 

 ment in many storages. 



The principle underlying this device is so simple that an occasional grower 

 may not bother to figure it out. Hence this brief review. An ordinary thermometer 

 (dry bulb) gives the temperature of the surrounding air. But if the bulb of a simi- 

 lar thermometer is enclosed by a piece of moist cloth or wick, and whirled to en- 

 courage evaporation of water, it will indicate a lower temperature than the dry bulb 

 because of the cooling effect of evaporation. The dryer the air the greater will be 

 the difference between the wet and dry bulb readings. But, if the air is saturated, 

 the moist cloth will neither lose nor gain moisture, so both thermometers will read 

 the same. In other words, the air holds as much moisture as it can possibly hold at 

 that temperature and its Relative Humidity is said tc be 100^, However, tbhe higher 

 the air temperature the more water it can hold. Thus, to figure the Relative Humidi- 

 ty in a storage on a particular day we must teiow not only the depression, or differ- 

 ence between wet and dry bulb readings, but the air temperature. With these tko 

 figures in mind we have merely to consult a simple table to get the Relative Hiomidity, 

 The lower reading is sometimes known as the "dew point" since it is the temperature 

 at which the air would tend to give up some of its moisture. Drops of devr collect 

 on a pitcher of ice water on a hot day as soon as the air immediately surrounding the 

 glass is lowered to the "dew point". And, obviously, the higher the Relative Humid- 

 ity the sooner will dew appear. 



The Relative Humidity in an apple storage should never fall below 90^, 

 But growers would be surprised to know how frequently it falls to 80^ or lower. 

 Only by making a periodic check-up (at least once a week) can actual moisture condi- 

 tions be determined, A dry floor is a danger sign. The following sample figures 

 show the relationships between depression, air temperature and Relative Humidity: 



Air 



Temp 



30°F 



32 



3U 



36 



38 



iiO 



Ii2 



hh 



ii6 



U8 



SO 



Depression (dry bulb-wet 

 bulb) 



Relative 

 Humidity {%) 



^i- ■)!• -i;- *■«■■«■•«• -;(■ ■•> ■«• ^ ^;- ■>;- 



Selling Fruit V/ith Vending Machines . "In 20 minutes the people of the United States 

 purchase over 2-1/2 million bars of candy and drinks of soda through vending machines. 

 If freshfruit had been made accessible to these people this same volume would amount 

 to 12-1/2 carloads. So in answer to the question, 'Are we missing something in mar- 

 keting?', we are definitely missing a good bet when we ignore the amazing possibili- 

 ties of merchandizing fresh ffruit in the coin-operated field, (Eastern Fruit Grower) 



