ODOUR OF TEA. 281 



Liebig is of opinion that the peculiar " odorous 

 principle of many vegetable substances is newly 

 formed during fermentation of the saccharine juices 

 of the plant. At all events," he observes, " it is a 

 fact that very small quantities of the blossoms of 

 the violet, elder, linden, or cowslip, added to a 

 fermenting liquid, are sufficient to communicate a 

 strong taste and smell, which the addition of the 

 water distilled from a quantity a hundred times 

 greater would not effect. The oil of the berries of 

 the elder-tree, many kinds of oil of turpentine, and 

 oil of lemons, possess a smell only during their 

 oxidation or decay." * 



" The leaves of the tobacco plant present the 

 same phenomena : when fresh they possess little or 

 no smell; but when the same plant, after being 

 dried, is moistened with water, tied together in 

 small bundles, and placed in heaps, a peculiar pro- 

 cess of decomposition takes place. Fermentation 

 commences, and is accompanied by an absorption 

 of oxygen ; the leaves become warm, and emit the 

 characteristic smell of prepared tobacco and snuff. 

 When the fermentation is carefully promoted, and 

 too high a heat avoided, this smell increases, and 

 becomes more delicate ; and after fermentation is 

 completed, an oily azotised volatile matter, called 

 nicotine, is found in the leaves. This substance, 

 nicotine, which possesses all the properties of a 



* Liebig's Chemistry of Agriculture, translation, 2d edit, 

 p. 320. 



