416 



Journal of the Department of Agriculture. 



The following table for obtaining' the relative humidity per cent, 

 will snfHee for the Western Province turkish tobacco grower: — 



Relative Hiiiiriditij Per Cent. — Fahrenheit Teniperatuies. 

 Barometric Pressure = 30.0 inches. 



From this table it will be seen that one is quite safe in keeping 

 the difference between the wet and dry bulb thermometers at from 2.5 

 to 3.5 when dealing Avith temperatures of 60° to 80° F.. the usual 

 temperatures encountered in regulated Western Province tobacco 

 barns in summer. A depression of 2.5 to 3.5 degrees registers at 

 such temperatures a relative humidity of 81 to 89 per cent., which 

 is near enough for all practical purposes in yellowing tobacco. How- 

 ever, these limits should not be exceeded. 



The above table will not always give accurate results it readings 

 of stationary wet and dry bulb thermometers in stagnant air are 

 employed. In such a case it might be necessary to substitute a sling 

 psychrometer (hygrometer). Furthermore, certain precautions must 

 be observed in preparing and fitting or renewing muslin covering of 

 the wet bulb. 



As it is diihcult to control the required relative humidity per 

 cent, when the temperature is high and wilting-room is continually 

 opened on account of freshly strung tobacco being taken in all day, 

 and on account of few sheds being absolutely ideal in practice, the 

 temperature in a turkish tobacco shed is kept in the vicinity of 70° F. 

 This temperature can easily be controlled in any fairly well con- 

 structed barn. By experience the grower soon learns without the 

 aid of a hygrometer whether the shed contains approximately the 

 right amount of moisture, simply by looking at and feeling the 

 tobacco, and by roughly judging the condition of the atmosphere 

 by its effects on the senses. 



