6 
N. C. AGRICULTURAL EXPERIMENT STATION. 
Ammonia ( NH S ) is always present in the cured tobacco in small 
proportions. It is supposed to be the product of fermentation. 
Cellulose (C 6 H 10 C$ foi ms from six to fifteen per cent, of the leaf, 
while the stalk contains from thirty to forty per cent. This material 
constitutes the frame-work of the plant, and bears an important 
relation to the character of the leaf. According to Nessler, the 
quality of tobacco for smoking increases to a certain extent as the 
cellulose increases, and that of the extractive substances diminish. 
Organic Substances .—Substances other than those previously enu¬ 
merated are present in tobacco, the nature of which has not been 
fully investigated. The character of some of these substances, which 
exist in the green plant, is entirely changed in the fermented product. 
Mineral Ingredients —The proportion of mineral ingredients in 
the leaf varies in different tobaccos from 8 to 27 per cent., while 
that of the stalk is very much less. The quality of the leaf is greatly 
influenced by the amount and nature of the mineral constituents. 
These constituents consist of combinations of potash, soda, lime, 
magnesia, phosphoric acid, iron, alumina, silica, chlorine, sulphuric 
acid, and sometimes a trace of manganese. These substances are 
present in varying proportions in different varieties, but there are 
usually large percentages of potash and lime present. It is gen¬ 
erally supposed that the presence of a large percentage of potash is 
beneficial for smoking purposes, while chlorine is generally con¬ 
sidered deleterious. 
