lug of cotton 



Pieces of-. 

 Matches 



EXERCISE 11 



Problem. What becomes of the substance taken from 

 the air when something burns? 



What to use. Piece of magnesium ribbon 8 inches 

 long ; scales ; weights ; funnel ; match ; cotton plug. 



What to do. Carefully balance the funnel which in- 

 closes the magnesium ribbon. Support the magnesium on 

 a cork, and bend it so that it does not touch at any point. 

 Ignite the free end ; be careful not to lose any of the ashes. 



Record. Tell all the changes that take place. 



Questions. 1. Is total weight of smoke and ash greater or less than that of original " fuel " ? 



2. How do you account for the difference ? 



3. How does the ash or smoke differ from the original magnesium ? 



4. What is the composition of the white powder? 



[12] 



