GOOD HEALTH 



In plants, leaves take the place of lungs, but the 

 strange thing is that during the daytime these leaves 

 breathe out the oxygen that we need, and breathe in the 

 carbon dioxid that we cannot use ; that is, they do the 

 opposite thing from what we do, and in that way they 

 help to keep our air pure by day. It is well, therefore, to 

 put plants in our living rooms. 



But after dark it is different, for now the plants give 

 out a little of the carbon dioxid that is bad for us, and so 

 they help to spoil the air while we are 

 sleeping. 



That explains what my nurse used 

 to do when I was ill. Every night she 

 took all the plants and flowers out of 

 my room and put them in the laundry. 

 She knew they were not good com- 

 panions for the night. 



Here is an interesting air experi- 

 ment. 



Light a small candle, set over it a 

 glass jar that fits down flat on the 

 table, and watch the flame. At first 

 it will burn as brightly as ever; then it will grow more 

 and more dim, until at last it will go out entirely. If you 

 should now put a mouse or bird into the jar, it would 

 die at once because the oxygen in the jar has been 

 used up by the candle. 



USING UP THE OXYGEN 



