22 SCIENCE OF HOME AND COMMUNITY 



skin becomes warm and saturated, and so retards further 

 evaporation and loss of heat, and the body becomes un- 

 comfortably warm. 



Colds and similar ailments, which are so common during 

 the winter, are not due usually to exposure to drafts, as is 

 often thought, but are caused generally by the unhealthful 

 conditions that too often exist indoors during the cold season ; 

 hot, dry, motionless air. The remedy for these ills is to re- 

 move the conditions that cause them. 



DEMONSTRATION 7 



Purpose. To learn the conditions necessary for a change 

 of air in ventilation. 



Apparatus. Candle, lamp chimney with even top, two 

 matches, cardboard. 



Directions, i. Light the candle, place the chimney over it. 

 Why does the candle go out? 



2. Light the candle again. On each side, place a match. 

 On the matches place the chimney and cover the top with the 

 cardboard. Why does the candle go out now ? 



3. Repeat the previous experiment, except that the card- 

 board is not placed over the chimney. Why does the candle 

 continue to burn? 



4. What do these experiments show ? 



Temperature. If the temperature is too high, the body 

 makes extra exertion by means of the sweat glands and 

 blood vessels to lower the temperature. As a result the 

 blood is drawn to the surface from other parts of the body, 

 and even then the body temperature may not be kept down 

 to the proper level. One of the most common causes of ill 

 effects from poor ventilation is too high a temperature. It 

 has been proved that the most healthful temperature for 

 the living rooms is between 65 and 70 degrees. When the 

 temperature becomes higher than 70, it produces feelings 



