EXERCISE 15 



WHAT IS THE TEMPERATURE AT WHICH THE WATE.R VAPOR CONDENSES 



IN THE ROOM? 



Materials. Same as in Exercise 14 ; the table on page 23, " Elements of General Science." 



Directions. Use the same apparatus as used in Exercise 14. Record the temperature of the room. 

 Stir the mixture of ice and water with a thermometer. Do not allow your breath to come in contact 

 with the cup. When the first clouding of moisture appears, read the thermometer and record the 

 temperature. Now remove the ice or snow and allow the cup to warm. When the last traces of 

 moisture disappear, read the thermometer again and record. Make several trials, and average all 

 readings. If your work has been accurate, this average reading is the approximate dew point (satura- 

 tion temperature) of the water vapor in the room at the time when the experiment was performed. 



What was the temperature of the room ? Was the air in the room saturated at that time, or at 

 what temperature would it have been saturated ? 



Additional problems. By reference to the table in the text find the weight of water vapor per cubic foot 

 present in the room at the time of the experiment. This is the absolute humidity. 



What is the weight of the water vapor in the entire room in which you are working ? 



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