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FUELS AND THEIR USES 



stoves and dull radiators? Still a third method of heat 

 transference is the passing of heat from one particle of 

 material to another. This is called conduction. A very 

 interesting experiment shown in the figure illustrates this 

 method of heat transference. The heat received by one 

 set of particles is passed on to others, and by them to 

 still others. Most metals are very good conductors. Some 

 substances, like glass, water, and many rocks, are fair con- 

 ductors, while air, wood, paper, and linen, silk, and woolen 

 fabrics are poor conductors. This principle of non-con- 

 duction is used in making the tireless cooker, the thermos 

 bottle, and the ice chest, where the heat is kept inside in 

 one case, and outside in the other. Solids are the best 

 and gases the poorest conductors of heat, air being one of 

 the best heat-insulating (non-conducting) materials. Con- 

 vection can take place only in liquids and gases. Remem- 

 ber that all these methods of transference of heat are at 

 work in heating our homes. 



Experiment. - 



Materials: 



- To see if heat will travel along a metal rod. 

 A metal rod 15 to 20 inches long. Ring stand and 



clamp. Burner. Wax. 

 Thread. 



Method: Tie a short 

 thread to each of six 

 tacks. Attach these two 

 inches apart to the 

 metal rod by means of 

 melted wax. Support 

 the metal rod so that 

 one end is in the flame 

 of the Bunsen burner. 

 Observation: Notice the 

 order of the melting of 

 the wax and dropping of the tacks. What does this suggest? 



Conclusion: What does this experiment teach about conduction of heat? 



