184 



Domestic Science 



more quickly than the iron, and the end of the copper 

 rod further from the source of heat reaches a higher 

 temperature than does the corresponding portion of 

 the iron. A more elaborate experiment may be done 

 if Ingenhaus's apparatus be available. 



EXPERIMENT 66. The apparatus referred to above 

 consists of a boiler of a rectangular shape, fitted with 

 corks along one vertical face, in which rods of different 

 metals but of equal length and diameter may be 

 inserted. The rods project to similar distances within 

 the boiler. The portions of the rods outside the 



Fig. 65. 



boiler are coated with paraffin wax by melting some 

 wax and applying it to the rods with a small brush. 

 Boiling water is poured into the heater and the rate 

 at which the wax melts is observed for each rod. When 

 no more wax is melted by the heat transmitted the 

 distances from the face of the boiler to the various 

 points on the rods at which the wax is still solid are 

 measured. The greater the distance, the better the 

 material transmits heat through its mass. 



121. This method of propagation of heat is termed 

 " conduction " and it is by conduction that heat passes 



