56 FIBST TEAR SCIENCE 



in the fireless cooker and the liquid in the thermos bottle 

 remains warm for a long time or, -if cold when put into 

 the bottle, it remains cold, as the heat from the outside 

 cannot reach it. Clothing is placed upon the body in 

 order to prevent the body heat from being conducted to 

 the surrounding air. 



28. The Measurement of Heat. Experiment 27. In each of 

 two beakers or tin cups weigh out 100 g. of watsr. Carefully heat 

 one of the beakers until the water when thoroughly stirred shows a 

 temperature of 90 C. Cool the other beaker till the temperature of 

 the water is 10 C. Pour the water from one beaker into the other, 

 and after thoroughly stirring note the resulting temperature. 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 remain, stirring the shot occasionally, until its temperature 

 is 90 C. Cool the water in the other beaker until its temperature is 

 10 C. Determine the temperatures exactly and then pour the shot 

 into the water. After thoroughly stirring determine the temperature 

 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, exert so much 

 influence upon the temperature of the surrounding air. 



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- 

 perature of equal quantities of different substances also 



