1 1 



just as soon as the candle is extinguished remove the paper 

 from the chimney-top and thrust in the Hghted spHnter. 



Qties. Why does the Hght on the spHnter go out ? 



Ans. Because there is no fresh air inside the chimney. 



Qucs. What became of the freshness that was in the air ? 



Ans. It was destroyed by the burning candle. 



Evidently there is some decided difference between fresh air 

 and air from which the freshness has been burned, since a flame 

 can continue to burn only in air that has the quality known as 

 freshness. This quality in fresh air is due to a gas which has 

 the name of oxygen, and which is represented by the letter O. 



Qiics. Why was the splinter put out instantly while the 

 candle flame died out gradually ? 



Ans. When the splinter was thrust in, the air had no fresh- 

 ness or oxygen at all, while when the candle was placed under 

 the chimney it had whatever oxygen was originally in the air 

 within the chimney. 



Endeavor to have this point clearly understood : that the 

 candle did not go out as long as the air had any oxygen and 

 that the splinter was extinguished immediately because there 

 was no oxygen left. Relight the candle. Our second question 

 may now be repeated : 



Qnes. Is anything else burning besides the candle ? 



A71S. Yes ; the oxygen of the air. 



When the subject of the necessity of fresh air and conse- 

 quently of oxygen for the burning of the candle seems to be 

 understood, the following questions, together with any others 

 which suggest themselves, may be asked. 



What is the reason that draughts are opened in stoves ? 



Why is the bottom of a " burner " on a lamp always full of 



holes ? 



II. Carbon. 



Let us now observe the blackened end of a burned match or 

 splinter. This black substance is usually known by the name 

 of charcoal and if handled will blacken the fingers. Try this. 

 The same substance is found on the bottoms of kettles which 

 have been used over a wood fire, only it is a fine powder. 



