50 LABORATORY MANUAL 



do you note in the ember? Where does the substance 

 come from that causes this change? This same sub- 

 stance is found in the air and is called oxygen. 



Examine the sides of the tube a little above the mer- 

 curic oxide. What do you find there? From what 

 substance did it come? Scrape it from the sides of 

 the tube and shake it out on to a piece of paper. Thus 

 mercuric oxide has been separated by means of heat 

 into its elements, oxygen and mercury. The process 

 of separating or decomposing a compound into its ele- 

 ments is known as chemical analysis. 



CHAPTER VIII 



CHEMICAL ELEMENTS 



Exercise 27. Carbon. 



Object: To determine some of the properties of 

 carbon. 



Apparatus 



Wood charcoal Pine splinter 



Lime water Crushed marble 



Test tube Dilute hydrochloric acid 



Beaker 



Directions : One of the forms in which carbon occurs 

 is charcoal. Examine a stick of wood charcoal. What 

 is the color? Is it soluble in water? Light the stick 

 of charcoal. Does it burn freely? Does it give off any 

 odor in burning? Thrust the lighted charcoal into the 

 mouth of a test tube containing some clear lime water. 



