NATUBE-8TUDY LESSONS. 169 



on the thermometer, the centigrade may be introduced 

 and its markings compared with those of the Fahrenheit. 



14. («) Thrust the thermometer into cold water. 

 {b) How does the column of mercury act ? 

 (c) Now, thrust it into hot water. 



{d) How does the mercury act ? 



{e) Hold the bulb against a piece of ice. 



(/) Compare the observation with that in the first 



case. 

 {£) Hold the bulb near a flame. 

 {h) Compare the effect with that in the second 



experiment. 



15. State how the mercury column acts under the 

 influence of high and low temperatures. 



16. (a) Place the thermometer in contact with sub- 



stances of different temperatures. 

 (3) Note the height of the column in each case. 



17. From your observations, state the relation between 

 the change in the mercury column and the change in 

 the temperature. 



18. Find the temperature of different objects, as — 

 different beakers of water, ice, the atmosphere of the 

 room, the hand, etc. 



19. Exercises for further observation : Determine: 



(a) At what temperature water freezes. 



(b) At what temperature water boils. 



{c) At what temperature the room is kept. 

 {d) The temperature of the body. 



(e) How temperature is affected by evaporation. 

 (/) How temperature is affected by sudden melt- 

 ings — -mixture of snow and salt. 



Note. — Carefully fill in that portion of your weather-chart relating to 

 the temperature of the atmosphere. 



