SPECIFIC HEAT OF AMMONIA. 



341 



duced by stirring did not sensibly raise the temperature of the mercury 

 above that of the container and the ammonia. This is, of course, not 

 strictly true. Readings were continued for ten minutes before the 

 heating current was applied, the changes of temperature during this 

 period being due to heat transfer to the surroundings and to the heat 

 of stirring. Exactly at the end of the tenth minute the heater switch 



t^ 



Figure 7. 



was closed and measurements of the energy input begun by an assist- 

 ant. The temperature of the mercury now began to rise rapidly, 

 and its value was recorded at intervals of one minute. When the 

 container was loaded with ammonia, this heating was continued for 



scale, and so arranged that the cross hair coincided with the center of the 

 second hand. The bridge was kept in balance by changing the slide wire and 

 at the instant the second hand came to the 60 second mark, the movement of 

 the sUde wire was stopped and the reading recorded. 



