CONDUCTION 23 



17. CONDUCTION 



Heat is conveyed from one body to another, or from one 

 part of the same body to another part, by means of the mole- 

 cules jostling against one another. If we heat one end of a 

 piece of copper wire, the other end soon becomes hot, because 

 the more rapidly moving molecules hit against their neigh- 

 bors. Not only do solids conduct heat, but liquids and gases 

 may convey heat in this method, although not as readily. 

 Materials which conduct heat are called conductors. There 

 are good conductors and poor conductors. 



This explains why metals and stone feel colder than wood 

 or cloth on a cold day, and warmer on a hot day, although 

 all of the objects are at the same temperature. In the pres- 

 ence of cold, therefore, good conductors will feel cold in com- 

 parison tb'some given body, and will take away its heat more 

 readily than will poor conductors. Similarly, in the presence 

 of heat, they will feel warmer than the body, and give up their 

 heat to it readily. 



References : 



1. 1803:215-219. Conduction. 



a. 1801 : 2S&-288. Conduction and Applications of Conduc- 



tion. 

 6. 1804:294-296. Conduction. 



b. 1805:322-325. Conduction. 



d. 1806:301-305. Conduction. 



e. 1807 : 164-166. Conduction. 

 /. 1808:216-217. Conduction. 



Experiment 8. Conduction. 



Apparatus: Burner, glass tube 6" long, copper and iron 

 wires No. 12, 6" long, test tube 6" x f ", test-tube holder, 

 a. Hold one end each of the glass tube and of the copper 



