10 



PRELIMINARY EXPERIMENTS 



1. OXYGEN 



Object. To prepare oxygen and to learn some of its 

 properties. 



Apparatus. An ignition tube, a small portion of red oxide of 

 mercury, a Bunsen burner, and a splinter of pine. 



Method. Place the mercuric oxide in the ignition tube 

 and heat it in the flame as in Figure 1. Note any change 

 of color. What collects on the inside of the tube ? How do 



you recognize this 

 substance ? Remove 

 some and examine it. 

 Plunge a charred 



'.mercury 



.Red .oxide 



splinter into the upper 

 end of the tube, be- 

 ing sure that there 

 is a glowing spark on 

 the end of the splinter. 

 What happens? Re- 

 peat the experiment 

 several times. What 

 must there be coming 

 from the oxide besides 

 what collects on the 

 tube? 



FIG. 1. Preparing oxygen. This is Oxygen. 



What color or other properties has this gas? What two 

 substances came from the oxide? 



Conclusion. Oxygen is , - , - , and supports 



combustion. 



Note. An alcohol lamp will seldom give sufficient heat to pro- 

 duce oxygen gas in any considerable quantity. In schools which 



