378 Our Surroundings 



The effects of tea and coffee, however, depend to a great extent 

 upon the method of preparation. In addition to the drugs already 

 mentioned, tea also contains an undesirable substance called tan- 

 nin. While caffein and thein are easily made soluble and quickly 

 diffused in hot water, tannin does not dissolve and will not diffuse 

 in the solution to any great extent except when boiled for some 

 time. Consequently tea should not be boiled. 



Cocoa and Chocolate. Cocoa and chocolate are also largely 

 used. They contain a small amount of a substance similar to 

 caffein, called theobromine, which might prove harmful if taken 

 in large doses. The small amount that exists in these drinks, 

 however, has practically no effect. Cocoa and chocolate used in 

 moderate quantities are agreeable and wholesome beverages for 

 most people. In addition, they have a food value since they con- 

 tain a considerable quantity of albumin and fat. 



Alcohol. While alcohol has no food value, various kinds 

 of beverages made from it are still extensively used in many 

 parts of the world despite the most conclusive proof that these 

 beverages, when taken habitually or in excess, are undoubtedly 

 harmful. The steady use of alcoholic drinks shortens life and 

 is the cause of much poverty, misery, and sickness. 



Some of the effects of excessive drinking of alcoholic bever- 

 ages have always been apparent. These include the loss of self- 

 respect and of pride in personal appearance, the weakening of 

 the will and the loss of self-control, the destruction or under- 

 mining of health, and the reduction of the working efficiency 

 of the individual. Other noticeable effects are the suffering 

 caused by poverty, the filling of poorhouses and hospitals for 

 the insane, and the terrible effects of heredity as shown in the 

 crippled organs and the defective senses of the young. 



Fermentation. Alcohol results from the fermentation of 

 liquid solutions of sugar or of other plant products which con- 

 tain sugar. Fermentation is a chemical change caused by yeast. 

 Sometimes this fermentation is caused by minute yeast organ- 

 isms which are always present in the air. In fermentation, 

 sugar is changed to carbon dioxide gas, which forms bubbles 

 and escapes, and to alcohol which remains in the liquid. 



