NON-LIVING THINGS 223 



Each is found to flash when heated to the point where it 

 vaporizes freely. To show that the blaze from burning 

 paper, wood, or coal is due to inflammable gases given off 

 by heating, try the following: 



To show gas from paper, cut strips of foolscap or other 

 heavy writing paper an inch and a half wide, and as long 

 as possible up to eighteen inches. Roll into tapers, folding 

 the larger end to prevent unrolling. Light the small end, 

 and after the flame has traveled up the lighter three or four 

 inches, note that there is still a flame at the small end, al- 

 though the paper is evidently burned. Blow the lower 

 flame out gently and observe that a dense gray " smoke " 

 pours out in its place. Collect a quantity of this in a wide- 

 mouthed bottle. Stop the bottle and set aside for a few 

 minutes. While waiting for this, repeat the experiment by 

 filling another bottle or a test-tube with the " smoke/' 

 While it is still hot apply the flame of the taper to it and 

 note that it flashes somewhat as did the vapor of gasoline, 

 leaving the bottle clear. Examine the bottle that was set 

 aside. If sufficient time has elapsed the " smoke " should 

 have entirely disappeared. Examine the sides of the bot- 

 tle for a yellowish liquid, creosote. Discuss the results 

 with the pupils. Was what we called smoke really smoke 

 or was it gas ? that is, an inflammable vapor ? Can this gas 

 be burned after it is cool, or must it be heated to reach its 

 flashing point? Repeat the experiment if necessary. 

 After burning some of the gas from the bottle, test the air 

 that remains for carbon dioxide. What is the result? 

 Draw from the pupils the fact that the heat of the flame 

 on the outside of the taper drives the gas off from the 

 inner surface. Why does not this burn at the point where 



