PRELIMINARY EXPERIMENTS 11 



are not supplied with gas, a gasoline stove or a kerosene vapor 

 stove can be used for experiments where considerable heat is re- 

 quired. 



An ignition tube is better than a test tube, since it resists the 

 heat. Test tubes in this experiment will often melt, and the oxide 

 will escape through a hole in the bottom. 



Definitions. An element is a simple substance. It can- 

 not be separated into any other substances. 



A compound is a substance that is composed of two or 

 more elements chemically combined. It can be separated 

 into its elements. 



In Experiment 1 the mercuric oxide is a compound con- 

 sisting of oxygen and mercury. By heating we separated 

 this compound into the elements oxygen and mercury. 



This process of separating a compound into its elements 

 is called analysis. 



2. CARBON 



Object. To learn some of the properties of the element 

 carbon. 



Apparatus. Charcoal, coal, coke, gas carbon, graphite, soot 

 (a diamond may be shown). A lamp, test tube, and a small quan- 

 tity of limewater. 



Method. Examine the various forms of carbon, but 

 confine the experiments to charcoal. Determine the color, 

 taste, smell, softness, brittleness, etc., of charcoal. Notice 

 its structure. What does this reveal as to its source ? Pul- 

 verize a little and shake it up in water. Is it lighter or 

 heavier than water ? Does it dissolve in water ? 



Hold a slender piece of charcoal in the lamp flame. What 

 occurs? Describe the color of the flame. Does it give 



