CHAPTER II 

 TEMPERATURE AND HEAT 



Temperature is not a measure of the amount of heat in a 

 body. If two similar basins containing unequal quantities 

 of water are placed in the sunshine on a summer day, the 

 smaller quantity of water will become quite warm in a short 

 period of time, while the larger quantity will become only 

 lukewarm. Both vessels receive the same amount of heat 

 from the sun, but in one case the heat is utilized in heating 

 a small quantity of water to a high temperature, while in the 

 second case the heat is utilized in warming a larger quantity 

 of water to a lower degree. Equal amounts of heat do not 

 necessarily produce equivalent temperatures, and equal tem- 

 peratures do not necessarily indicate equal amounts of heat. 

 It takes more heat to raise a gallon of water to the boil- 

 ing point than it does to raise a pint of water to the boiling 

 point, but a thermometer registers the same temperature in 

 the two cases. The temperature of boiling water is 100 C. 

 whether there is a pint of it or a gallon. Temperature is in- 

 dependent of the quantity of matter present ; but the amount 

 of heat contained in a substance at a certain temperature is not 

 independent of quantity, being greater in the larger quantity. 



The unit of heat. It is necessary to have a unit of heat, 

 just as we have a unit of length, or a unit of mass, or a unit of 

 time. One unit of heat is called a calorie, and is the amount 

 of heat which will change the temperature of I gram of watei 

 i C. It is the amount of heat given out by I gram of watei 

 when its temperature falls i C., or the amount of heat ab- 



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