INTRODUCTORY EXERCISES 19 



apparatus, and should be allowed to escape. When the 

 bubbles of gas flow freely through the delivery tube, fill 

 one of the bottles with water and invert over the delivery 

 tube to receive the gas (oxygen) as in the above diagram 

 (see Exercise II on page 10). When the bottle is full cover 

 with the glass plate and set aside mouth upward. Fill the 

 other four bottles in the same way. Then proceed as fol- 

 lows: 



A. Examine the gas in the first bottle. Has it any color? 

 odor? Suck a little into the mouth with a glass tube. Has 

 it any taste? 



B. Tie a piece of charcoal to the handle of the deflagra- 

 ting spoon, heat the end of the charcoal until it glows, and 

 introduce it into the second bottle. Describe the result. 

 Keep lowering the charcoal as it tends to stop burning, until 

 it reaches the bottom of the bottle. Compare this result with 

 that of Ex. VII. What name do you give to this process? 

 How could you test the contents of the bottle to prove your 

 statement? Do so and record result (see Ex. VII). 



C. Place in the bowl of the deflagrating spoon a piece 

 of phosphorus the size of a pea (Caution! Handle 



with forceps and cut under water). Light the 

 phosphorus and introduce quickly into the third 

 bottle. Describe the result. Does it burn more or 

 less brilliantly than in air? Note the white cloud 

 in the bottle. (This is an oxide of phosphorus and 

 is formed by the uniting of the phosphorus and 

 the oxygen.) Compare this result with that in B. 



D. After cleaning the deflagrating spoon place 

 some powdered sulphur in it. Light the sulphur. 



Note how it burns in air and the color of the flame. FlG> 6 - 

 Now introduce it into the fourth bottle. Describe the re- 



