468 SOLANACEiE. 



does not concrete even at - 10° C. It has a strongly alkaline reaction, 

 an unpleasant odour, and a burning taste. It quickly assumes a brown 

 colour on exposure to air and light ; and appears even to undergo an 

 alteration by repeated distillation in an atmosphere deprived of 

 oxygen. Nicotine dissolves in water, but separates on addition of 

 caustic potash ; it occurs in the dried leaves to the extent of about G 

 per cent., but is subject to great variation. The seeds of tobacco are 

 stated by Kosutany^ as grown in Hungary to contain from 0'28 to 067 

 per cent, of the alkaloid. 



It has not been met with in tobacco-smoke by Vohl and Eulenberg 

 (1871), though other chemists assert its occurrence. The vapours were 

 found by the former to contain numerous basic substances of tlie 

 ])icolinic series, and ceded to caustic potash, hj^drocyanic acid,- sul- 

 phuretted hydrogen, several volatile fatty acids, phenol and creasote. 

 There was further observed in the imperfect combustion of tobacco the 

 formation of laminse fusible at 94° C, and having a composition C'®H'^ 

 Oxide of carbon is also largely met with. 



Tobacco leaves, whether fresh or dried, yield when distilled with 

 water a tui'bid distillate in which, as observed by Hermbstadt in 1828, 

 there are formed, after some days, crystals of Nicotianin or Tobacco 

 Caniplior. According to J. A. Barral, nicotianin contains 712 per cent, 

 of nitrogen (1). By submitting 4 kilogrammes of good tobacco of the 

 previous year to distillation with much water, we obtained nicotianin. 

 Moating on the surface of the distillate, in the form of minute acicular 

 crystals, which we found to be devoid of action on polarized light. 

 The crystals have no peculiar taste, at least in the small quantity we 

 tried ; they have a tobacco-like smell, perhaps simply due to the water 

 adhering to them. When an attempt was made to separate them by a 

 filter, they entirely disappeared, being probably dissolved by an accom- 

 panying trace of essential oil. The clear water showed an alkaline 

 reaction partly due to nicotine ; this was proved by adding a solution 

 of tannic acid, which caused a well-marked turbidity. Nicotianine is 

 in our opinion a fatty acid contaminated with a little volatile oil as in 

 the case of Capsicum (.see page 454), or Iris (see article Rhizome Iridis). 



Among the ordinary constituents of leaves, tobacco contains albumin, 

 resin and gum. In smoking;, these substances, as well as the cellulose 

 of the thick midrib, would yield products not agreeable to the con- 

 sumer. The manufacturer therefore discards the midrib, and endea- 

 vours by further preparation to ensure at least the partial destruction 

 of these unwelcome constituents, as well as the formation of certain 

 products of fermentation (ferment-oils), which may perhaps contribute 

 to the aroma of tobacco, especially when saccharine substances, liquorice, 

 or alcohol, are addad in the maceration to which tobacco is subjected. 



Tobacco leaves are remarkably rich in inorganic constituents, the 

 proportion varying from 16 to 27 per cent. According to Boussingault, 

 they contain when dry about 1 per cent, of phosphoric acid, and from 

 3 to 5 per cent, of potash, together with 2\ to 4| per cent, of nitrugen 

 ))artly in the form of nitrate, so that to enable the tobacco plant to 

 flourish, it must have a rich soil or continual manuring.* 



^ DragendorfF's JahresbericJd, 1874. 98. ^ For further particulars on the chemis- 



^ Poggiale and Marty (1870) stated hydro- try of tobacco cultivation see Boussing.ault, 

 cyanic acid to be absent. Ann, de Chim. et de Phya. ix. (1866) 50. 



