178 CONDUCTION. 



A. Because (in windy weather) the 

 particles of air pass over us more rapidly ; 

 and every fresh particle takes from us 

 some portion of heat. 



Q. Show the wisdom of God in making the 



AIR a BAD CONDUCTOR ? 



A. If air were a good conductor (like 

 iron and stone) the heat would be drawn 

 50 rapidly from our body, that we must 

 be chilled to death. Similar evils would 

 be felt also by all the animal and vege- 

 table world. 



Q. Does not the bad conducting power of air 

 enable persons to judge whether an EGG be NEW or 

 STALE ? 



A. Yes ; touch your tongue against 

 the shell at the larger end; if it feels 

 warm to the tongue, the egg is stale ; if 

 not, it is new-laid. 



Q. Why will the SHELL of a STALE EGG feel 

 WARM to the tongue ? 



A. Between the shell and the f ' white 

 of the egg" there is a small quantity of 

 air, which expands in a stale egg, from 

 the shrinking of the white. 



Q. Why does the expansion of air (at the end 

 of an egg) make it feel WARM to the tongue ? 



