64 Our Surroundings 



Tooth Pastes and Powders. The value of tooth pastes and 

 tooth powders, which are so extensively used, lies in the fact 

 that they contain alkaline substances which counteract the bad 

 effect of the acid substances that form in the mouth and at- 

 tack the teeth. Care should be taken not to use tooth powders too 

 freely since they sometimes contain material which will injure the 

 teeth. 



Tooth paste contains a soap to aid in the cleaning of the 

 teeth, some substance such as milk of magnesia for neutralizing 

 the acids in the mouth, often something that will destroy any 

 germ life that may exist in the mouth, and some flavoring such as 

 peppermint or wintergreen. 



SUMMARY 



Water is a colorless, odorless and tasteless compound of two 

 gases oxygen and hydrogen. 



Water is widely distributed on the surface of the earth, cov- 

 ering nearly three-fourths of its area. 



Bodies of water are among the greatest modifiers of climate. 



Large bodies of water, by making the climate milder, help the 

 growth of crops that are raised near their shores. 



Water has many uses, the most important of which is its aid 

 in sustaining the life of all living things. It gives us our fish 

 supply and affords healthful recreation. 



Water will flow and exert pressure. Upon these properties 

 depends much of its value to man. 



Sources of home water supply are wells, rivers and lakes, from 

 which water is often obtained by pumping. 



Sanitary control of the sources of water supply is most essen- 

 tial. Every possible effort should be made to prevent pollution of 

 water intended for drinking. 



Water is an essential agent in the disposal of sewage. 



Proper plumbing is necessary to keep sewer gas from entering 

 houses. 



Water is a great solvent. 



The manufacture of artificial ice from water is an important 

 industry. 



