430 Introduction to the Study of Science 



munity. Explain the ground upon which you base your classification 

 of the utilities listed. 



What kinds of furniture are made of iron or steel ? What advantages 

 are gained in using such material for furniture ? What disadvantages ? 

 What interior finishings of office or public buildings are made of steel 

 and iron? What advantages are there in having window and d(or 

 frames and the doors and finishings of the rooms made of steel or steel 

 covered? Why are steel passenger cars better than the common 

 wooden cars? Why are steel or iron rods and rails used in concrete 

 structures as viaducts, bridges, and buildings? 



Visit a blacksmith shop and learn what different kinds of iron are 

 used. For what purposes are the different kinds? What properties 

 of iron make it especially useful ? Can it be readily shaped as desired ? 

 Can it be welded ? 



What iron industries are there in your community? What sort of 

 raw material do they use? What are their chief products? 



Cast iron, which is converted into useful objects in very many 

 localities, is easily worked and has a comparatively low fusing tem- 

 perature. Visit, if possible, an iron foundry. Study the kinds of 

 molds or patterns. What are the chief products of the foundry? 

 What sort of iron is used for castings? How is it prepared in the 

 foundry? How long a time is required to melt the cast iron? In 

 what kind of furnace is this done ? What fuel is used ? Why ? 



World production. The relative tonnage of iron and other 

 metals for a year shows the importance of iron in the world's 

 production. We may take pig iron as equivalent to the total 

 output of metallic iron. The production of pig iron in 1910 

 amounted to more than 96 per cent of the world's total output 

 in tonnage of metals. The value of the pig iron was about 46 

 per cent of the total value of the metals produced. 



The United States' production. The United States, which is 

 the largest producer of iron, had in 1910 a total output of 

 minerals worth considerably more than two thousand.. million 

 dollars. This includes all minerals used in construction, as 

 clay and stone with their products, lime, and cement, and also 

 all fuels, as coal, petroleum, and natural gas. But if we 

 exclude minerals and fuels and consider only the metals, such as 

 lead, copper, aluminium, zinc, silver, gold, and iron, we have a 



