STIMULANTS, NARCOTICS, AND POISONS 63 



And in a similar way we may rightfully use some of the 

 substances we have named above, if we make sure that we 

 use these stimulants in moderation.- We should always re- 

 member, however, that a stimulant causes only temporary 

 increase of activity, and that if we apply it too frequently 

 or in too great quantity to a horse or within our bodies, it 

 soon loses its power to bring about even a temporary in- 

 crease of activity, and that then it comes to do absolute 

 harm. 



Definition of a Narcotic. Another class of substances that 

 we sometimes use has an effect directly opposite to that of 

 stimulants. Ether, morphine, and chloroform, for example, 

 do not quicken any process in the body, as do stimulants, 

 but on the contrary lessen the degree of activity. Hence, 

 instead of comparing the action of such substances to that 

 of a whip on a horse, we may liken them to the bit and reins 

 when they are used to check the motions of the animal. 

 Any compound that acts in this way is called a narcotic, 

 which we may define as " any substance that directly induces 

 sleep, blunts the senses, and in large amounts produces com- 

 plete insensibility" 



The terms stimulant and narcotic that we have just de- 

 fined naturally suggest a discussion of the use and abuse of 

 tea and coffee, tobacco and alcohol, and to that discussion 

 we will now turn. 



2. TEA AND COFFEE 



Use and Abuse of Tea. " Tea should be used only in 

 the form of an infusion, made by pouring boiling water 

 upon the right amount of tea leaves, and allowing it to stand 

 a short while to l draw.' ' : For this purpose about a spoon- 

 ful of tea should be used to every cup of water. Tea should 

 never be put on the stove to boil, for two reasons : in the 

 first place, by this treatment the delicate taste and odor are 

 lost ; and, in the second place, if the tea infusion is boiled, 

 the tea leaves give out a chemical known as tan'nin } which 



