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process, the principal changes in composition brought 

 about in the curing are dependent on the life activities 

 of the minute cells of the leaf, and the nature of the 

 changes in the two methods is the same. The main 

 difference lies in the extent or completeness of these 

 changes. The typical bright yellow tobacco is harvested 

 riper than tobacco which is cured without the use of heat. 

 Partly on this account and also because of the character 

 of the soil on which it is grown, this type of leaf is 

 relatively richer in starchy matter and poorer in organic 

 nitrogenous materials. Because of the difference in 

 composition combined with the effects of high tempera- 

 tures and more rapid drying, the green colour is removed 

 much more rapidlv. The rapid appearance of the yellow 

 colour does not afford sufficient time for the transforma- 

 tion of all the starchy matter and as soon as this stage is 

 reached the drving must be hastened so as to prevent any 

 further change in colour. Evidently, then, the flue 

 curing method consists essentially in the hastening and 

 shortening of the first stage in the air-curing process, 

 while the second stage of the cure, made apparent bv the 

 development of the brown colour in the case of cigar 

 tobacco, is not allowed to take place at all. 



The capacity of the air for holding moisture, and 

 consequently its drying capacity, depends principally on 

 its temperature ; and air which is already saturated has 

 no drving power until its temperature is raised. Satis- 

 factory curing can only be accomplished by proper regu- 

 lation of the rate of drying ; and this depends chiefly on 

 the humidity of the air in the barn. From these facts it 

 is clear that in order to maintain a definite rate of drving 

 by controlling the humidity, the temperature in the barn 

 must hear a certain relation to that of the outside air ; 



