78 EXPERIMENTAL GENERAL SCIENCE 



with the gas, supplies the additional oxygen necessary for com- 

 plete and rapid burning, and consequently produces great heat. 



Practical Exercises 



1. Prepare a bottle of oxygen by some of the methods suggested. 

 What color is oxygen? 



2. Test the gas with a glowing but not blazing splinter. Will oxygen 

 burn? 



3. How does oxygen compare with air as a supporter of combustion? 



4. Untwist the strands at one end of a piece of picture wire. Wrap 

 one strand about the head of a match. Light the match and when 

 burning well lower into a bottle of oxygen. Explain the result. 



5. Prepare carbon dioxide as directed and test it with a lighted 

 splinter. Will carbon dioxide burn? 



6. Will carbon dioxide support combustion? 



7. Catch another test-tube of the gas and pour into it about 10 cubic 

 centimeters of lime-water. Shake it well and note the result. This is 

 an infallible test for carbon dioxide. 



8. Put about 5 cubic centimeters of lime-water into a clean test-tube 

 and try to pour a test-tube of carbon dioxide into it. Which do you 

 conclude is heavier, carbon dioxide or ordinary air? 



9. Light a candle end and place it in the bottom of a clean, dry fruit 

 jar or wide-mouthed bottle. Cover the mouth of the jar with a sheet of 

 glass or cardboard and let it stand for a few minutes. What change 

 takes place in the candle flame. Why? 



