that an article so widely used cannot produce _any marked deleterious effect_. for it must meet some instinctive craving of the human being,as bread and salt meet his absolute needs,to be so widely sought after and consumed. fashion does not rule this habit, but it is equally grateful to the savage and the sage. and it cannot be so ruinous to body and mind as some reformers assert; otherwise, in the natural progress of causes and effects, whole nations must have already been extinguished under its use. many mighty nations have used it for centuries, and show no aggregated deterioration from its employment. individual exceptions exist in every community. they arise either from idiosyncrasy or from excess, and they have no weight in the argument. now, what are these qualities and these effects? we can best answer the first part of the question by a quotation. in ministering fully to his natural wants and cravings, man passes through three successive stages. first, the necessities of his material nature are provided for. beef and bread represent the means by which, in every country, this end is attained. and among the numerous forms of animal and vegetable food a wonderful similarity of chemical composition prevails. second, he seeks to assuage the cares of his mind, and to banish uneasy reflections. fermented liquors are the agents by which this is effected. [they are variously produced by every people, and the active principle is in all the same, namely, alcohol.] third, he desires to multiply his enjoyments, intellectual and animal, and for the time to exalt them. this he attains by the aid of narcotics. and of these narcotics, again, it is remarkable that almost every country or tribe has its own, either aboriginal or imported; so that the universal instinct of the race has led, somehow or other, to the universal supply of this want or craving also. these narcotics are opium, hemp, the betel, coca, thorn-apple, siberian fungus, hops, lettuce, tobacco. the active principles vary in each, thus differing from foods and stimulants. our business is now to inquire into the chemical constituents of tobacco. the leaves of this plant owe their properties to certain invariable active principles, which chemistry has enabled us to separate from those ingredients which are either inert or common to it and other forms of vegetation. they are two in number,a volatile alkali, and a volatile oil, called _nicotin_ and _nicotianin_, respectively. a third powerful constituent is developed by combustion, which is named the _empyreumatic oil_. starch, gum, albumen, resin, lignin, extractive, and organic acids exist in tobacco, as they do, in varying proportions, in other plants. but the herb under consideration contains a relatively larger proportion of inorganic salts, as those of lime, potassa, and ammonia,and especially of highly nitrogenized substances; which explains why tobacco is so exhausting a crop to the soil, and why ashes are among its best fertilizers. the organic base, _nicotin_, (or _nicotia_, as some chemists prefer to call it,) exists in tobacco combined with an acid in excess, and in this state is not volatile. as obtained by distillation with caustic soda, and afterwards treated with sulphuric acid, etc., it is a colorless fluid, volatilizable, inflammable, of little smell when cold, but of an exceedingly acrid, burning taste, and alkaline. nicotia contains a much larger proportion of nitrogen than most of the other organic alkalies. in its action on the animal system it is one of the most virulent poisons known. it exists in varying, though small proportion, in all species of tobacco. those called mild, and most esteemed, seem to contain the least. thus, according to orfila, havana tobacco yields two per cent of the alkaloid, and virginia nearly seven per cent. in the rankest varieties it rarely exceeds eight parts to the hundred. the same toxicologist says that it has the remarkable property of resisting decomposition in the decaying tissues of the body, and he detected it in the bodies of animals destroyed by it, several months after their death. in this particular it resembles arsenic. _nicotianin_, or the volatile oil, is probably the odorous principle of tobacco. according to some, it does not exist in the fresh leaves, but is generated in the drying process. when obtained by distillation, a pound of leaves will yield only two grains; it is therefore in a much smaller proportion than the alkaloid, forming only one half of one per cent. it is a fatty substance, having the odor of tobacco-smoke, and a bitter taste. applied to the nose, it occasions sneezing, and taken internally, giddiness and nausea. it is therefore one of the active constituents of tobacco, though to a much less degree than nicotin itself. for while hermstadt swallowed a grain of nicotianin with impunity, the vapor of pure nicotin is so irritating that it is difficult to breathe in a room in which a single drop has been evaporated. when distilled in a retort, at a temperature above that of boiling water, or burned, as we burn it in a pipe, tobacco affords its third poison, the _empyreumatic oil_. this is acrid, of a dark brown color, and having a smell as of an old pipe, in the pores of which, particularly of meerschaum clay, it may be found. it is also narcotic and very poisonous, one drop killing reptiles, as if by an electric shock: in this mode of action it is like prussic acid. but this empyreumatic oil consists of two substances; for, if it be washed with acetic acid, it loses its poisonous quality. it contains, therefore, a harmless oil, and a poisonous alkaline substance, which the acetic acid combines with and removes. it has been shown to contain the alkaloid nicotia, and this is probably its only active component