206 CHAPTER XII 



heat is raised to 95° F. and held until the colour begins to 

 spread. The temperature is then increased to 100° F. until the 

 yellow colour becomes more pronounced. During this time the 

 atmosphere of the barn should be kept moist to prevent the leaf 

 from drying. This is when the hygrometer is invaluable. 

 Enough moisture must be kept in the atmosphere of the barn 

 during this period, so that the temperature registered by the 

 wet bulb of the hygrometer will not be more than 3° to 4° 

 below that registered by the dry bulb. If a depression of 3° 

 could be maintained the leaf would yellow more rapidly and 

 more uniformly. When the wet bulb registers more than 4° 

 below the dry bulb it indicates that the atmosphere in the barn 

 is becoming too dry, and artificial moisture must be introduced 

 into the barn. This can be done by wetting the walls below 

 the tobacco, by pouring water over the floor, or by placing wet 

 bags on the flues. When the leaf begins to show a distinctly 

 yellow colour the temperature is increased to 110° F., and held 

 until the leaf is practically yellow, when the heat is raised to 

 115° F. and held until the leaf takes on the proper yellow 

 colour. From 100° F. to 115° F. the amount of moisture in 

 the atmosphere of the barn is reduced until the wet bulb 

 registers from 6° to 7° below the dry bulb. 



When the tobacco is properly yellowed the barn must be 

 so managed that no further change of colour takes place in the 

 leaf. This is the critical stage in curing, and requires the 

 closest attention and the most careful manipulation. If the 

 atmosphere of the barn is too humid, or if the ventilation is 

 not sufficient and the temperature is not increased fast enough, 

 moisture will collect on the surface of the leaf and the tobacco 

 will turn a reddish-brown colour, or "sponge," which de- 

 creases its value. On the other hand, if too much ventilation 

 is given, and the temperature is increased too rapidly, the leaf 

 will be killed too quickly and a greenish red or black colour 

 will develop, which greatly reduces the value of the leaf. The 

 proper conditions are maintained when the barn is so ven- 

 tilated that the moisture is carried off as fast as it comes to 

 the surface of the leaf, and the temperature is so regulated 

 that the colour will be fixed in fifteen to eighteen hours. 



To secure these conditions the bottom and top ventilators 

 should be slightly opened and the fires increased to maintain 

 the temperature at 115° F. The ventilation and heat are in- 

 ci-eased and the temperature kept at 115° F. until the tips of 

 the leaves begin to curl, when the temperatiu'e is increased to 



