116 THE WONDERFUL HOUSE THAT JACK HAS 



bonic acid gas must have been breathed out of our 

 lungs. 



If we breathe into a bottle for a short time and then, 

 without allowing other air to get in, place a lighted 

 candle or splinter inside, the light will quickly go out. 

 This is because most of the oxygen has been breathed 



Breathing into a jar through a 

 tube or hollow stem, passed 

 through a card. What happens 

 to a lighted candle inserted 

 into the jar? Explain this. 



The bottle has been inverted on 

 the table, the card slipped 

 away, and the lighted candle 

 lifted into the bottle to see 

 whether it will still burn. 



out, and the carbonic acid gas which has been breathed 

 in will not support combustion. If a mouse or other 

 small animal is placed under a glass receiver where 

 no air can get in, it will begin to show signs of discom- 

 fort as soon as its own breathing has considerably 

 increased the carbonic acid gas and decreased the 

 oxygen. Its distress will grow as unrenewed air 

 continues to be breathed. The moment fresh air is 



