226 



Messrs. Rosa and Smith on a Calorimetric 



amount of heat is to be brought away, the water is made to 

 enter at a low temperature and to flow rapidly through the 

 absorbers. If a smaller quantity of heat is to be absorbed 

 and carried away, the entering water will be warmer, and its 

 gain in temperature correspondingly less. By varying the 

 temperature of the water and its rate of flow, the rate of 

 absorption can be varied between wide limits, and kept very 



Fig. 3. 



nicely at any desired point. In practice the thermometer A' 

 is the guide in regulating the temperature of the entering 

 water. If the temperature of A begins to rise (A 7 , as already 

 stated, can be read to one-thousandth of a degree), the entering 

 water is slightly cooled; if to fall, it is slightly warmed ; the 

 rate of flow of water, after being once adjusted for a given 

 experiment, is maintained constant. 



In order to measure the quantity of heat thus carried 

 away, the thermometers E and F are inserted in two small 

 reservoirs, M and N, which stand in the wooden wall of the 

 calorimeter between the two copper surfaces. The thermo- 

 meter E indicates the temperature of the water just as it 

 enters the chamber A, and the thermometer F gives its tem- 

 perature as it leaves. The difference of temperature multiplied 



