THE MEASUREMENT OF HEAT 



83 



one of the beakers until the water when thoroughly stirred shows 

 a temperature of 90 C. Cool the other beaker till the tempera- 

 ture of the water is 10 C. Pour the water from one beaker into 

 the other, and after thoroughly stirring note the resulting tempera- 

 ture. Use a chemical thermometer to determine the temperatures. 

 Weigh out 100 g. of fine No. 10 shot in a tin cup and 100 g. of 

 water in another. Place the cup containing the shot in boiling 

 water and allow it to re- 

 main, stirring the shot occa- 

 sionally, until its tempera- 

 ture is 90 C. Cool the 

 water in the other beaker 

 until its temperature is 

 10 C. Determine the tem- 

 peratures exactly and then 

 pour the shot into the 

 water. After thoroughly 

 stirring determine the tem- 

 perature of the mixture. 

 Which has the highest 



temperature, the mixture of water and water or the mixture of shot 

 and water? 



Since heat plays such an important part in the activities 

 of the earth, we need to know how to measure it. There 

 is a great difference between temperature and the amount 

 of heat. The amount of heat in a spoonful of water at 

 100 would be very much less than in a pailful of water 

 at 10. It would require more heat to raise a pond of 

 water a small part of a degree than to raise a kettleful 

 many degrees. That is why large bodies of water, although 

 their temperatures never greatly change, are able to absorb 

 and to give out great amounts of heat. 



Not only does the amount of heat necessary to raise the 

 temperature of different quantities of the same substance 

 vary, but the amount of heat necessary to raise the tem- 



FIQURE 38. A SELF-RECORDING 

 THERMOMETER 



