4 LABORATORY EXERCISES. 



and insert the burning piece of carbon 

 into the bottle, closing the mouth with 

 the stopper. What do you observe? 

 Suggest an explanation of this fact. 

 4. (Dem.) Remove the stick, pour into the 

 bottle a little clear lime-water, and 

 shake. What change do you observe 

 in the lime-water? (When carbon burns 

 it combines with the oxygen gas of the 

 air, forming oxid of carbon, more com- 

 monly known as carbonic-acid gas or 

 carbon dioxid.) How, then, can the 

 presence of carbon dioxid be demon- 

 strated? 



E. Mineral matters. 



1. Burn a match as long as you can. What 



are some of the physical properties of 

 the ashes? (The ashes represent the 

 mineral matter of the wood, carried up 

 from the earth in the sap. When the 

 water of the sap evaporated, the solid 

 substances were left behind as a part of 

 the wood.) 



2. Heat these mineral matters as hot as you 



can. Will they burn? 



3. How could you determine, therefore, 



whether or not a substance contained 

 mineral matter? 



F. Summary. 



i. Name in order the parts of a match that 

 will burn, beginning with the most in- 

 flammable. 



