40 



or less degree, the action of these agents. The best 

 examples of the force of habit are observed in the power 

 which most individuals may acquire of resisting the 

 sickening, poisonous influence of tobacco, and in the 

 extraordinary power of opium eaters in withstanding the 

 effects of large doses of opium. The same power exists 

 also in some intemperate persons of resisting the influence 

 of alcoholic liquors; but here it is not observed to nearly 

 so great an extent as with tobacco and opium. 



The animal economy is excited by many agents besides 

 these. Most of the ordinary physical agents, such as 

 light, heat, and cold, are stimulants when applied mode- 

 rately, and, like the medicinal class of stimulants, they 

 cause two actions — primary excitement, and secondary 

 depression — the first being produced by the less, and the 

 second by the greater, application. Thus, a warm bath 

 is at first stimulant, but depression afterwards takes place, 

 and may even cause fainting. The long continued appli- 

 cation of heat, in warm climates, exerts a depressing and 

 weakening effect upon the natives of cold climates. A 

 slight degree of cold invigorates the body. Momentary 

 immersion in a cold bath is exciting, but, long continued, 

 it depresses all the powers of life ; and the extreme cold of 

 the arctic regions has so powerful a depressing influence, 

 that it renders the circulation languid, and sometimes 

 causes drowsiness, sleep, and death. 



With these general observations on the action of 

 stimulants and narcotics, I proceed to speak of the effects of 

 alcohol, which constitutes the active part of all fermented 

 and spirituous liquors. 



When alcoholic liquids are taken into the stomach, they 

 are absorbed and carried into the circulation. The stomach, 

 to which the fluid is directly applied, and the liver, through 

 which it must pass on its way into the general circulation, 

 are most directly excited, and hence these organs very 

 frequently become diseased through intemperance. The 

 alcoholic fluid, having entered the blood, produces a more 

 or less stimulant effect on every part of the system ; but its 

 action is most perceptibly exerted upon the brain, the heart, 

 the lungs, skin, and kidneys. Soon after any spirituous 

 liquor has been taken, the heartbeats quicker and stronger, 

 and the surface of the body becomes redder, while its tem- 

 perature rises. Liebeg supposes that this heating effect is 

 caused by the carbon and hydrogen of the alcohol combining 

 with the oxygen, which unites with the blood at the lungs ; 

 and this seems highly probable, both from the fact that no 



