OXYGEN 9 



dioxide (about a tablespoonful in all) on a piece of paper, and 

 then pour them into the test tube. Insert glass tube in cork, 

 place in test tube, and hold test tube by ring stand obliquely. 

 Place rubber tube over glass tube, and put other end of rubber 

 tube under the mouth of a bottle which has been filled with 

 water and inverted in the pneumatic trough, which should be 

 half full. of water. Heat the test tube slowly. A gas will soon 

 come off and fill the bottle. This gas is oxygen. Collect four 

 bottles of gas, and cover each, when full, with a glass plate. 



6. Light a splinter of wood and then blow out the flame, 

 obtaining a glowing coal on the splinter. Insert this in a 

 bottle of oxygen. What happens ? 



c. Take a piece of picture cord 6" long, hold it with tweezers 

 by one end, dip the other end in sulphur, and light the sulphur. 

 When you get some burning sulphur on the wire cord, insert 

 it in a second bottle of oxygen. Describe the results. 



d. Burn a piece of magnesium ribbon partly in air, but 

 mostly in oxygen. Conclusions? 



e. Burn charcoal in air and in oxygen. Note that there 

 is no flame. 



The results of this experiment strengthen our conclusion 

 in Experiment 1, that the act of combustion requires the 

 presence of some substance from the air. We see that oxygen 

 produces the same results as air, but much more vigorously, 

 because it is not diluted with other gases which are present in 

 the atmosphere. Where there is a sufficient supply of oxygen, 

 there is complete combustion and no smoke. Smoke always 

 indicates unburned fuel, and therefore means waste. 

 References : 



1. 1703 : 24-29. Oxygen : Its Preparation and Characteristics, 

 a. 1612 : 9-10. Oxygen in the Soils. 

 6. 1612 : 53-54. Properties of Oxygen. 



