2. TOBACCO—NICOTINE.
§ 328. The different forms of tobacco are furnished by three species of the tobacco plant, viz., Nicotianum tabacum, N. rustica, and N. persica.
Havanna, French, Dutch, and the American tobaccos are in the main derived from N. tabacum; Turkish, Syrian, and the Latakia tobaccos are the produce of N. rustica. There seems at present to be little of N. persica in commerce.
All the species of tobacco contain a liquid, volatile, poisonous alkaloid (Nicotine), probably united in the plant with citric and malic acids. There is also present in tobacco an unimportant camphor (nicotianin). The general composition of the plant may be gathered from the following table:—
TABLE SHOWING THE COMPOSITION OF FRESH LEAVES OF TOBACCO
(POSSELT AND RIENMANN).
| Nicotine, | 0·060 | ||
| Concrete volatile oil, | 0·010 | ||
| Bitter extractive, | 2·870 | ||
| Gum with malate of lime, | 1·740 | ||
| Chlorophyl, | 0·267 | ||
| Albumen and gluten, | 1·308 | ||
| Malic acid, | 0·510 | ||
| Lignine and a trace of starch, | 4·969 | ||
| Salts (sulphate, nitrate, and malate of potash, chloride of potassium, phosphate and malate of lime, and malate of ammonia,) | - | 0·734 | |
| Silica, | 0·088 | ||
| Water, | 88·280 | ||
| 100·836 | |||
§ 329. Quantitative Estimation of Nicotine in Tobacco.—The best process (although not a perfectly accurate one) is the following:—25 grms. of the tobacco are mixed with milk of lime, and allowed to stand until there is no odour of ammonia; the mixture is then exhausted by petroleum ether, the ether shaken up with a slight excess of normal sulphuric acid, and titrated back by baryta water; the sulphate of baryta may be collected and weighed, so as to control the results. With regard to the percentage of nicotine in commercial tobacco, Kosutany found from 1·686 to 3·738 per cent. in dry tobacco; Letheby, in six samples, from 1·5 to 3·2 per cent.; whilst Schlössing gives for Havanna 2 per cent., Maryland 2·29 per cent., Kentucky 6·09 per cent., Virginian 6·87 per cent., and for French tobacco, quantities varying from 3·22 to 7·96 per cent. Again, Lenoble found in Paraguay tobacco from 1·8 to 6 per cent.; and Wittstein, in six sorts of tobacco in Germany, 1·54 to 2·72 per cent.
Mr. Cox[350] has recently determined the amount of nicotine in a number of tobaccos. The results are tabulated in the following table as follows:—