226 TOBACCO LEAF. 



escape of water from the leaves is at first comparatively 

 slow. Goff thinks this "furnishes a warrant for the 

 practice of many intelligent tobacco growers, who hold 

 that it is better to keep the curing house nearly closed 

 for a time after the tobacco is hung, and that it should 

 be gradually opened as the curing proceeds," but of 

 course this point depends to some extent upon atmos- 

 pheric conditions, if the leaf is to be cured naturally. 



Artificial Curing. Frear modified the yellow cur- 

 ing process for seedleaf at the Pennsylvania station 

 (referred to heretofore), as follows, getting a complete 

 cure in about 16 days : 



In this work, no great difference in yield of cured 

 leaf was found in artificial over natural curing. But 

 the former gave a leaf tissue and veins as thin as the 

 slow air-curing process does. The final thickness seems 

 chiefly determined by the conditions under which the 

 plant was grown. 



Wisconsin Experiments. Two years' work at the 

 Wisconsin experiment station, by E. S. Goff, have 

 brought out the following valuable points. 



Moist air is lighter than dryer air at a given temper- 

 ature, and hence tends to rise. Comparatively dry air 

 entering the curing house near the ground and coming 

 in contact with tobacco that is giving off moisture, as it 

 absorbs this water will gradually rise through the build- 

 ing, absorbing more and more moisture in its course, 

 until it reaches the roof. It is important, therefore, 

 not only that the curing house shall contain ventilators 

 through the roof or in the gables, but that these be so 



