OXYGEN 



33 



and while the splinter is still glowing, thrust it into the cylinder 

 again. Observe the result in each case. (2) Put a small piece of 

 sulfur, a little larger than a grain of wheat, into the iron or defla- 

 gration spoon ; ignite in the flame, and 

 then thrust into another cylinder of O. 

 Observe the result. (3) Take a piece of 

 bright fine iron wire or watch-spring, and 

 make it into a spiral with a loop at one 

 end. Warm the wire by holding it near 

 the flame, then hold the loop for an in- 

 stant in the flame and dip it into some 

 sulfur which has been placed on a piece 

 of paper. Hold again in the flame for a 

 moment and then place at once in the 

 third cylinder of O. In order to insure 

 the success of this experiment, the wire 

 should be very fine, free from rust, and 

 held in the flame only long enough to 

 start ignition, and then placed in the 

 cylinder. 



Questions, (i) Where does the O in the cylinder come from ? 

 (2) What caused it to separate from the compound? (3) What is 

 the appearance of O ? (4) Compared with air, is it a light or heavy 

 gas ? (5) What caused the splinter to burn and to rekindle ? (6) 

 What product was formed when the splinter was burned? (7) 

 What caused the sulfur to burn? (8) What product was formed 

 when the S was burned? (9) Why do these materials burn differ- 

 ently in O than in air? (10) What caused the iron to bum, and 

 what was formed ? ( 1 1 ) Is O combustible ? ( 12) Is O a supporter 

 of combustion ? (13) What compounds are always formed by the 

 union of O with an element? (14) Give the properties and char- 

 acteristics of O as observed from this experiment. 



The oxygen in potassium chlorate is not held in firm chemical 

 combination, and when the substance is heated, first a portion, and 

 finally all of the oxygen is given off. The manganese dioxid is 

 used because of its physical action upon the potassium chlorate, 



3 



Fig. 15. Testing oxygen 

 with burning splinter. 



