The active principle of tobacco is nicotin, which resides in the leaves in combination with malic acid. Nicotin is an alkaloid, and one of the most deadly poisons known. In distilled form, nicotin, even in minute quantities, produces death almost instantaneously. The nicotin contained in a pound of tobacco is sufficient to kill several hundred men if administered in the form of pure nicotin, but in smoking and chewing tobacco only a small amount of this poison is absorbed into the body at one time, and, owing to the gradual growth of the tobacco habit, the system has time to partly adjust itself to the use of this powerful drug, enough at least to prevent acute narcotic poisoning. The violent sickness caused by the first use of tobacco evidences the poisonous effects of the nicotin upon a body not accustomed to its use. Tobacco as a narcotic is not as drastic in its effect as opium, morphin, and cocain; for this reason its use is not so generally condemned. Popular opinion, however, is now rapidly recognizing that all of these substances belong in the same general class and are deteriorating factors in human development. The rapid spread of the cigarette habit among young boys has done much to arouse popular agitation against the tobacco evil. [Sidenote: General effect of tobacco] From the standpoint of health, nothing can be said in favor of the use of tobacco in any form, as it gradually deadens the sensitiveness and control of the nervous system. It preys with great violence upon the optic nerves, and more than any other drug known dethrones sexual vitality. The tobacco heart, which is readily recognized by medical practitioners, shows the effect of this narcotic upon the nervous system. The craving for tobacco is closely related to the craving for intoxicating liquors and for highly seasoned food--three of the most potent factors in perverting the true sense of taste and arousing abnormal cravings which destroy natural hunger. Neither tobacco nor nicotin are now used by medical practitioners. Tobacco was formerly used as a purgative, and also as a poultice to relieve swellings and inflammation. COFFEE [Sidenote: Composition of coffee] Coffee is one of the most extensively used articles in the narcotic group. The alkaloid which gives coffee its characteristic properties is caffein. Coffee also contains from three to four per cent of tannic acid. Other substances in coffee, to which the pleasant odors and taste are due, are various forms of fats and carbohydrates, but these exist in such small quantities as to be negligible food elements. The effect of the caffein is that of a nervous stimulant, increasing the general nervous and mental activity. Coffee is frequently used to keep people awake. It is given as an antidote for opium poisoning because it stimulates the nervous system and prevents sleep. [Sidenote: Effects of coffee-drinking]