THE ELEMENTS THAT PLANTS USE 6l 



der and meerschaum as an earthy material. Magnesium 

 powder burns with a strong, active light, and is used 

 for flashlights with the camera. 



Aluminum. This light metallic substance is familiar 

 to all, since its employment in making useful things of 

 all kinds: for the kitchen, the nursery, etc. It is re- 

 markable for its resistance to oxidation. It is found in 

 all clays, and thus forms a large part of many of our soils. 



Iron. We all know this element. It is the most com- 

 mon and most useful of our metals. It is also of common 

 occurrence throughout the earth. It combines readily 

 with oxygen, as iron rust, hence the brown and red color 

 of fields where much of this element is present. Iron is 

 readily oxidized (rusted) when moisture is present. The 

 farmer is never called upon to supply this element as a 

 fertilizer, since it always is present in the soil sufficiently 

 to supply the needs of plants. 



