CHAPTER II 



TEMPERATURE AND HEAT 



14. Temperature not always a Measure of the Heat 

 Present. 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 

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

 second case the heat is utilized in warming to a lower degree 

 a larger quantity of water. 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 boiling 

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

 but a thermometer would register 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 any temperature is not in- 

 dependent of quantity, being greater in the larger quantity. 



15. 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 water i C.; it is the amount of heat given out by I gram 

 of water when its temperature falls i C., or the amount of 

 heat absorbed by I gram of water when its temperature rises 



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