104 



(b) Cold contracts air. 



(c) Location of hot and cold air in room. 



4. Experiments. 



(1) Fit a glass tube with a rubber tubing on the end of it into a 



cork. Fit the cork in a test tube, making it air tight. 



Place the end of the rubber tubing in a glass of water. 



Heat the test tube. Why do the bubbles come up through 



the water? 



Heat expands the air. Expanded air presses equally in 



all directions and finds the easiest egress through the tubes 



and water. 

 ( 2) Partially fill a small top rubber balloon or bladder with 



air. Securely tie the opening, making it air tight. Place 



in a vessel of cold water and heat slowly. When the air has 



become expanded remove and plunge into cold water. 



Account for the result. 

 (3) Ascend a step ladder carrying a thermometer. Account for 



the difference in the reading "of the thermometer. 



5. Study of Flame. 



(a) Dark zone no combustion. 



(b) Illuminated zone partial combustion. 



(c) Mantle complete combustion. 



6. Experiments. 



(1) Place matches successively in the dark zone, illuminated zone, 



and mantle of a candle. Is there any difference in the time 

 of igniting? Which zone is hottest? 



(2) Place a match or splinter across a flame. Which zone burns 



the stick most? Which least? 



(3) Press a sheet of white cardboard, held horizontally, upon the 



flame of a candle, almost down to the wick. Remove care- 

 fully. Which zone deposited the most soot? Which least? 

 Why? 



7. Experiments with Carbon Dioxide. 



(1) Burn a candle or splinter in a jar of air forming carbon di- 



oxide. Pour lime water into the jar of carbon dioxide and 

 note change in appearance of limewater. 



(2) Breathe through a glass tube 'into a jar of lime water. Note 



change in appearance of lime water. Compare results of 

 the two experiments and account for phenomena. 



(3) Place a glass containing lime water on the floor of the school 



room; on the window sill; near the top of the room; outside 

 of the window exposed to the fresh air. Leave for twenty- 

 four hours. Compare water in the different glasses and 

 give reasons for the change, if there be any. Relate to pre- 

 vious experiments. 



