CARBON 49 



carbon as a reducing agent may be observed from the fol- 

 lowing experiment : 



Experiment 5. Mix thoroughly 2 or 3 grams of copper 

 oxid (CuO) and an equal bulk of charcoal (animal charcoal). 

 Place the mixture in a small test-tube and apply heat. Observe the 

 result. 



Questions. ( i ) What is the bright red material produced in the 

 test-tube? (2) What was the source of this material? (3) What 

 caused the O to be separated from this compound ? (4) What did 

 it unite with? (5) What was formed as the product ? (6) Write 

 the reaction. (7) Why is carbon called a reducing agent? (8) 

 What kind of an agent would CuO be called? (9) Why is carbon 

 useful in separating minerals from their ores ? 



When carbon acts as a reducing agent, it unites with or abstracts 

 the oxygen from the material reduced, forming CO 2 . The process 

 is called reduction because the oxygen is abstracted. When oxy- 

 gen is added to a material, the process is just reversed, and is called 

 oxidation. When reduction takes place, oxygen is abstracted from 

 a material. When oxidation takes place, oxygen is added. 



53. Combustion. From the facts given in regard to 

 oxygen and carbon, it is evident that combustion, in the 

 ordinary sense, is simply the union of carbon with oxy- 

 gen, and, as a result, light and heat are given off. If the 

 process is a slow one, and heat without light is evolved, 

 slow oxidation takes place. An example of slow oxida- 

 tion is the rusting of metals. In slow oxidation, the total 

 amount of heat evolved is the same as if the material un- 

 derwent direct combustion. The regulation of drafts 

 in stoves to influence the combustion of fuel so as to ob- 

 tain the largest amount of heat, is based upon the simple 

 laws of the combustion of carbon. 



A candle or gas flame well illustrates the laws of com- 



