212 TOBACCO LEAF. 



says that the yellowing process should be done at 90 

 (80 if the weather is cool), and should last from 18 to 

 30 hours, until the desired color is obtained. The dry- 

 ing, or curing, is then effected by regulating the tem- 

 perature so as to have 95 for two hours, 100 for two 

 hours, 105 for two hours, 110 for two hours, 115 for 

 two hours, 120 for six hours, 130 for two hours, 140 

 for two hours, 150 for two hours and 160 for 24 hours, 

 tlie last temperature being kept up until the stalks and 

 stems are cured. 



A very interesting case was reported by the Border 

 Review. A barn 18 feet square, four firing tiers high, 

 and containing 450 sticks, or 3150 plants, was success- 

 fully cured by the following process : The tobacco was 

 of old-field growth, long leaf, but thin and light. The 

 temperature was run up to 90 in six hours, then to 100 

 in six hours, then 110 in six hours. The leaf was thor- 

 oughly yellowed at the expiration of 18 hours. The 

 temperature was then advanced 120 in six hours; to 

 125 in six more ; to 130 in six hours ; to 140 in three 

 hours, where it was allowed to remain for six hours. 

 At the end of this time the leaf was cured. Then the 

 temperature was run up to 150 for three hours and 

 held at that point for three hours, then to 170 in 12 

 hours, where it stood for 12 hours, until the stalk was 



already contains more or less of moisture, the more moisture the air 

 contains, the less rapid will be the evaporation, and vice versa. Since 

 water, in evaporating, absorbs heat, the temperature of the wet bulb 

 is lowered more or less, according as the evaporation is more or less 

 rapid. Hence, by noting the difference in the temperature registered 

 by the two thermometers, we form an idea of the moisture of the air, 

 the greater the difference registered, the dryer the air, and vice 

 versa. When the two thermometers register alike, the air in contact 

 with the wet bulb is saturated with moisture, so that it can hold no 

 more, and hence evaporation lias ceased. In dry, summer weather, 

 the difference registered by the two thermometers may amount to fif- 

 teen or more degrees. By using prepared tables, the absolute relative 

 humidity of the air may be determined by the psychrometer, but for 

 our present purpose, the depression of the wet bulb is all that is nec- 

 essary to use. The tobacco leaves while in process of curing being 

 moist, the evaporation from them will follow the same law as from 

 the wet bulb, hence a psychrometer hung among the plants in the 

 curing house will give an indication at any time of the rate at which 

 the moisture is passing off from the tobacco. 



