PLANT FOODS 25 



and the water is perfectly clear. Pour off this clear 

 liquid into another bottle. This clear liquid is lime 

 water. Some of the lime has been dissolved. Taste 

 it to satisfy yourself. Now pour some of the lime 

 water into a tumbler and with a straw blow bubbles 

 through it. It gets milky because of the carbon 

 dioxide in your lungs. Now mix up some more "soda 

 water" and add vinegar. Carefully tip the tumbler so 

 that the gas can run into the lime water. It is heavier 

 than air and will run over the edge of the tumbler 

 like water. Shake the lime water. It is milky again. 

 This shows that the gas given off by the soda water 

 when vinegar is added is the same as the gas given off 

 by your lungs. Make one more experiment : 



Place a little lime water in a saucer and set this on 

 the floor in your sleeping room over night. In the 

 morning it, too, will be found to be milky. This shows 

 the presence of carbon dioxide in the air. 



Magnesia. Magnesia is known to most of us. It is 

 the white powder used to whiten the skin and prevent 

 soreness from the wind. 



Potash. Potash is found in wood ashes and gives 

 to lye, made therefrom, its soapy feel. 



Sources of Plant Foods. The water, soil and air 

 are the sources of plant foods. The air contains two 

 ammonia and carbon dioxide soil and water the 

 other nine. All of these foods except carbon dioxide 

 dissolve in water and enter the plant by its roots. 

 Carbon dioxide is taken in directly from the air by the 

 plant through the little holes in the leaves. 



