﻿THE CULTURE OF FLUE-CURED TOBACCO. 33 



stopper, to be closed or opened more or less us the conditions of 

 curing require. 



Generally it will be found best to begin to open these ventilators 

 and raise the heat somewhat before the tobacco is fully yellow, so 

 that the moisture will be sufficiently exhausted by that time to pre- 

 vent reddening or sponging. The draft should not be too strong, 

 especially at first, but it should be sufficient to effectively remove the 

 air before, or at least by the time, it becomes saturated. 



In light-bodied tobacco, as grown on the lighter soil types, the 

 yellowing process will generally take about 36 to 48 hours under 

 average conditions; but if the tobacco is very heavy and dark, as 

 frequently occurs on the filler soil types in the western part of the 

 Old Belt section, it may be necessary to consume three or four days 

 in the yellowing process. This will be especially necessary if the 

 soil on which the tobacco was grown was rich in ammoniates or if the 

 tobacco w~as a little underripe when harvested. Under these cir- 

 cumstances there will be an abnormal quantity of reserve nitrogenous 

 food material in the leaf, and it will be necessary to avoid applying 

 much heat for several days or drying the leaf much, in order that 

 these food materials may be consumed by the life processes of the 

 plants, else the tobacco will be rank smelling, dark, and objection- 

 able rather than sweet and agreeable. This explains why it is such 

 a common practice with those who grow tobacco on the more clayey 

 soils of the western part of the Old Belt to let the tobacco hang in 

 the barn for a day or two before any fire is used at all and then to 

 keep the temperature comparatively low so as to prolong the yellow- 

 ing period, which in this case is really a ripening or sweetening 

 period as well. 



When the yellowing of the leaf is approximately completed, dur- 

 ing the later stages of which the temperature has been maintained 

 perhaps at from 110° to 120° F., it is then the custom to move up 

 the temperature quite rapidly, say at the approximate rate of 2^ 

 degrees per hour, to 130° or 135°, and to hold it at that point until 

 the leaf itself is entirely dry throughout the barn, or at least on the 

 bottom poles. It is a general rule of curing that it is not safe to exceed 

 this temperature for any length of time before the leaf is dry, because 

 at about this temperature, or a little above, the cells of the leaves are 

 rapidly killed, and when killed they at once release the moisture they 

 contain, which comes immediately to the surface and results at once, 

 by oxidation, in a blackish discoloration known as scalding. Scald- 

 ing may occur at a much lower temperature than this when the 

 tobacco is full of sap, in the early stages of the cure. When the leaf 

 is dry throughout the barn the ventilators may be partially or per- 

 haps wholly closed, to save fuel, and the heat gradually moved up 

 at the rate of about 5 degrees per hour to about 175° for the light, 



