164 COMMUNICATION OF HEAT. 



A. The white crust is the salt of 

 the water left on the clothes by 

 evaporation. 



Q. Why does this WHITE CBDST always DIS- 

 APPEAR in WET weather ? 



A. In wet weather the moisture of the 

 air dissolves the salt ; and, therefore, it 

 no longer remains visible. 



Q. Why should NOT persons, who take violent 

 exercise, WEAR very THICK CLOTHING ? 



A. When the heat of the body is 

 increased by exercise, perspiration reduces 

 the heat (by evaporation) to a healthy 

 standard : as thick clothing prevents this 

 evaporation, and confines the heat and 

 perspiration to the body, it is injurious to 

 health. 



CHAPTER XIII. 

 COMMUNICATION OF HEAT. 



1. --CONDUCTION. 



Q,. How is HEAT COMMUNICATED from one 

 body to another ? 



