29 



() Put some limewater in a clean beaker, and by means 

 of a piece of clean glass tubing, blow 

 into the limewater (Fig. 22). Does 

 any change occur in it? If so, ex- 

 plain why. 



(c) Put some limewater in a test 

 tube and insert in the upper part of 

 the tube a burning match or cigar. 

 (Do not let the burning substance 

 come into contact with the lime- 

 water.) After the match has burned 

 for about a minute, remove it, insert 

 a cork in the test tube, and shake 

 the limewater. Does any change 



OCCUr in it ? If SO, explain why. FlG - 22. -Testing the breath 



J for carbon dioxide. 



Can you suggest any way of re- 

 ducing the amount of carbon dioxide in a school room ? 



EXPERIMENT 19. DISTILLATION OF COAL AND WOOD 



(a) Put some small shavings of wood into a strong test 

 tube and connect with a bottle as shown in Figure 23. 

 Heat the tube gently at first and then strongly, and notice 

 any change which takes place in the wood. While the 

 wood is burning bring a lighted match near the exit tube C. 

 What happens ? How do you account for the strange re- 

 sult? 



(b) Allow the tube to cool and examine what remains of 

 the wood. What has been formed from the original wood ? 



The separation of a substance into simpler substances by 

 means of heat and without a sufficient supply of oxygen is 

 called Destructive Distillation, 



