66 TALKS ABOUT THE SOIL. 



soils. It is yellow in color, and burns with a blue 

 flame and suffocating smell. 



7. Phosphorus. This is a pale-yellow matter, that 

 burns so easily that it has to be kept under water. It 

 unites with other elements to form valuable plant-foods. 

 Without these compounds in the soil, it is difficult to 

 make any plants grow. It is essential in every soil, 

 and it forms a part of every plant. 



8. Chlorine. This element is a gas of yellow-green 

 color, and is quite poisonous. Combined with sodium 

 it forms chloride of sodium, or common salt. Com- 

 bined with other elements it is found in all plants and 

 soils. 



These elements are called the non-metallic elements. 

 The remainder of the fourteen elements found in soils 

 are metals. They are as follows : potassium, sodium, 

 calcium, magnesium, aluminium, and iron. The po- 

 tassium and sodium form, with other elements, impor- 

 tant parts of all soils. Calcium, with oxygen, forms 

 lime ; and in the rocks it forms a part of marble, lime- 

 stone, and chalk ; and as these rocks are weathered, 

 it appears in many soils. In one form this element 

 makes an important compound called gypsum, which 

 forms an important part of our soils. Magnesium is 

 found in certain limestones ; and aluminium is in all 

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

 Iron we all know. It is the most common of the 

 metals, and in various compounds is abundant every- 

 where in the earth. In our soils it is usually combined 

 with oxygen, as iron-rust, and gives the red and brown 



