LABORATORY EXERCISES. 



(This is an evidence that chemical 

 action is taking place.) 



b. Feel of the bottle. What is a second 



proof of chemical action? 



c. What do you see at the free end of the 



delivery -tube? This gas is hydro- 

 gen. 



Fill a test-tube with water and invert it 

 over the mouth of the delivery-tube. 



a. What other gas is collected in a sim- 



ilar way? 



b. Wrap the tube in a towel, still hold- 



ing it upside down, and hold the 

 mouth near a burning match. 

 What do you hear? 



Potassium 

 fermanganat 



FIG. 3. 



c. If an explosion occurs, fill the tube 

 with hydrogen a second time. 

 When the gas burns quietly, col- 

 lect a bottle as you collected the 

 oxygen, but keep it upside down 



