298 



Our Surroundings 



before it is converted into the ordinary iron of commerce or 

 into the stronger structural steel. The slag, also, is drawn off 

 while in a liquid state and later is used in manufactures of 

 different kinds. From some slags a good quality of cement is 

 made. 



FILLING MOLDS WITH MOLTEN METAL 



Origin of Soil. We are all familiar with soil. We know 

 that it is necessary to the growth of plant life, but few of us know 

 what it actually is. Soil is composed of both inorganic and organic 

 matter. The inorganic part is formed by the weathering, 

 or breaking up, of rock into very small particles by water, 

 wind, glaciers, ice, air and, to a lesser extent, by plants and 

 animals. The organic part of soil is derived from plants and 

 animals. 



Water. Water erodes, or eats into, rock. The softer the 

 rock the more rapidly the water washes away particles. During 

 heavy storms, torrents rush down the sides of mountains often 

 bringing masses of stones. Year in and year out these rub against 

 the rock surface of the mountains and gradually reduce a large 



