TOBACCO. 



Besides its inorganic (mineral) elements — lime, potash, soda, magnesia, 

 alumina, ferric oxide, phosphorous, sulphur, chlorine, and silica — it contains the 

 following organic substances: starch, glucose, albuminoids, resinous and fatty 

 compounds and the vegetable acids, pectic, citric, malic, oxalic, and acetic. And 

 of the combinations of organic elements there are found in tobacco nicotine, 

 nicotianine, celluloid, and chlorophyl. 



RIPENING OP TOBACCO. 



After the plant has attained its full growth, the leaves cease to expand and 

 " granulation, due to the distention of the individual cells of the leaf through 

 accumulation of inter-cellular substance begins," which in North Carolina and 

 Virginia usually takes place from five to six weeks after topping, hastened or 

 retarded, according to season, soil, and time of planting. Then, if the weather 

 is dry and favorable for a few days longer, the color changes rapidly from green 

 to a pale yellowish green, as the plants get ready for the knife. The main cause 

 of the change in the color of the leaves is due to the chlorophyl — ^the coloring 

 matter in leaves- — ^being changed to xanthrophyl. 



CHANGES- IN TOBACCO INDUCED BY FLUE CURING. 



The temperature of 90 to 100° Fahr. continued for 30 to 36 hours under the 

 tobacco, induces slight fermentation, expands the leaf cells and starts the sap tOj 

 the surface, when evaporation commences in earnest. The vegetable acids, act-r 

 ting on the starch, glucose and albuminoids, produce at first slight fermentation 

 — somewhat after the ripening of an apple or pear, and causes a'change of color 

 in the leaf, superinduced by the same reasons or agencies which induce change 

 in the color of a ripening apple or pear. 



In the chemical changes produced in the incipient curing stages — ^the yellow- 

 ing of the leaves — sugar is formed, ammonia evolved and chlorophyl changed into 

 xanthyne. Now, if the temperature is raised slowly at this stage of the drying 

 process, so as not to oxidize the organic properties in the leaf, the color is pre- 

 served till the leaf is dried. But a too rapidly advancing temperature causes 

 oxidation and discoloring, or rather reddening of the leaf, sometimes to the extent 

 of scalding — virtually cooking it. And so, if the heat is not properly advanced and 

 adjusted and fermentation too long continued, the yellow color fades into brown. 

 To so regulate the color by heat as to catch and fix it in the leaf while sap is 

 being expelled and the leaf dried, is the science of curing yellow tobacco. 



What is termed " sweating " during the curing process is the accumulation of 

 sap, driven by the heat to the surface of the leaves more rapidly than the ventila- 

 tion will enable the hot dry air to absorb. And whenever this condition occurs, the 

 experienced curer knows it results from inadequate or imperfect ventilation. For, 

 whenever the ventilation is properly adjusted, there will be no sweating — the 

 current of warm or hot dry air induced by the draft will take up — absorb— the 

 moisture thrown to the surface as fast as it is evolved. " Sponging" is produced 

 by oxidation caused by fermentation too long continued, and indicates the inci- 

 pient stage of what is called "house-burn," "pole-sweat," or "barn-rot." Proper 

 ventilation as well as heat, is necessary to so dry the leaf without sweating or 



