160 NATURE STUDY 



The following experiments will decide these questions 

 and some others : 



Place some fresh leaves in a bottle of water, which 

 should then be placed in a fruit jar. Suspend in the 

 same jar a small bottle of clear lime water. Close se- 

 curely and cover with black paper, or set it in a perfectly 

 dark closet. The jar must be absolutely air tight. 



Prepare another jar in the same way, omitting the 

 lime water. 



The next day exhibit the first jar. 



What has happened to the lime water ? Why ? Where 

 must the carbon dioxide have come from ? "What does 

 this indicate ? 



Into the other jar, lower a bit of burning candle sus- 

 pended by a wire. Owing to the presence of carbon 

 dioxide it will immediately cease to burn. To show 

 that this is not due to the shape of the jar, introduce 

 the burning candle into a similar empty jar. 



In which jar did the candle go out ? What is the 

 difference between the two jars ? Why, then, do you 

 think that the candle went out in one jar but not in the 

 other ? What two tests are there to prove the presence 

 of carbon dioxide ? 



Set up this experiment in the same way, but put the 

 jar where the leaves will be in a strong light. 



Test for carbon dioxide. Explain to the children why 

 this time the candle does not go out. If the aquarium 

 is flourishing and in a good light, they can see the little 

 bubbles of oxygen given off by the plants. 



How shall we find out whether seeds breathe ? 



Set up one experiment in the light and the other in 



