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Introduction to the Study of Science 



When the jar is full of gas, cover with glass and remove, invert, and 

 leave covered. Fill the other bottles in the same way, covering closely 

 with glass or wet filter paper. When all the bottles are full, remove 

 the rubber tubing from the water and take the flame at once from 

 the test tube. If water enters the test tube, it will cause trouble 

 and perhaps injury. 



Exercise : Oxygen and combustion. Make the following tests 

 with the collected gas. After every test close each bottle promptly 

 to retain the products of combustion for later tests. 



1. Char a splinter or match and then bring it to a glow, not a flame. 

 A Chinese joss stick is better, for it glows easily. Insert in a bottle. 



Fio. 22. Potassium chlorate is decomposed by heat, liberating oxygen, which 

 is captured in a bottle over water. Candle burning in jar of oxygen. 



What happens? Repeat this until the reaction fails to occur. Does 

 the gas make combustion take place? Does the gas burn? Does 

 it seem to be a good supporter of combustion? 



2. In a second bottle of oxygen insert a lump of charcoal by means 

 of a deflagrating spoon or a piece of wire. Keep the bottle closed as 

 much as possible while the charcoal is left there. What takes place? 

 Remove and heat the charcoal to a bright red glow. Introduce it" 

 into the same bottle. What is the result? What does this indicate 

 as to the temperature of substances igniting in oxygen? Must they 

 be at a kindling temperature? 



3. Put into a bottle enough dry sand to cover the bottom about 

 one half inch deep. Cover bottle quickly to prevent escape of gas. 



