NON-LIVING THINGS 2IQ 



that they are both deficient in oxygen and contain an excess 

 of carbon dioxide. Collect another jar of breathed air. 

 If the breath is held for a few seconds the results will be 

 more positive. Test for oxygen. It does not support a 

 flame. Place a branch of some plant with fresh green 

 leaves upon it in the jar. Invert the jar into a vessel of 

 water as before, and put it into the sunlight. After two 

 or three hours, test for oxygen ; it will be found to be pres- 

 ent. Test for carbon dioxide. It has been absorbed by 

 the plant and water. 



Place a mixture of equal parts of pulverized potassium 

 chlorate and " black oxide " in a test-tube. Cork with a 



bored cork, which has tightly fitted into it 

 Qx en a delivery tube composed of eight or ten 



inches of quarter inch glass tube and about 

 two feet of rubber tubing. Heat the test-tube over an al- 

 cohol or gas lamp, and collect by displacement the gas that 

 is thus generated. This gas is oxygen. Test it by thrust- 

 ing into it a piece of charcoal with a small spark of fire 

 upon it, or a burning splinter after the blaze is extinguished, 

 leaving a tiny, glowing coal at the end. In the oxygen 

 these tiny sparks spring into life and burn fiercely. In a 

 gas that so actively supports combustion green twigs, thin 

 pieces of steel, as watch springs, and fine wire, burn bril- 

 liantly, and drops of the molten metal fall to the bottom of 

 the jar. Two or three inches of water left in the bottom 

 of the jar will cool these and prevent the glass cracking in 

 the intense heat. 



In a bottle holding about a quart, put a few marble chips 

 or a couple of ounces of baking soda, and add water until 



