IRON AGE 



3061 



IRON CROSS 



The total amount of combined and uncom- 

 bined carbon present in iron is largely regu- 

 lated through the heat applied in its manufac- 

 ture. Though pure iron does not melt below 

 2,741 F., it begins to undergo changes at 1,400. 

 At 1,652 it begins to absorb carbon, and as it 

 does so its melting point is lowered, so that 

 iron which contains 4.3 per cent carbon melts 

 at 2,066 F. 



Rust. This is in effect a partial burning of 

 the iron, and therefore weakens it. For this 

 reason bridges and other steel structures are 

 usually coated with a waterproof paint before 

 the final color is applied, and other forms of 

 iron are galvanized, or coated with zinc. The 

 Indians, though ignorant of iron, used its 

 oxide, or rust, for red paint, and we ourselves 

 admire the beautiful colors which it gives to 

 rubies. 



Magnetism. This affects all iron, but is 

 retained only by the harder forms. By utiliz- 

 ing the principle that soft iron ceases to be a 

 magnet when the electric current is shut off, 

 it has been possible to produce the telephone, 

 the telegraph and the valuable electro-magnef. 

 Iron heated to 1,400 F. loses its magnetic 

 properties. Magnetite ore gives iron of greater 

 magnetic properties than other varieties, and 

 pure iron is a better conductor of electricity 

 than carbonized iron. 



The specific gravity of iron is 7.85; that is, 

 it is 7.85 times as heavy as water. E.S. 



Consult Lindgren's Mineral Deposits; Eckles' 

 Iron Ores: Their Occurrence, Valuation and Con- 

 trol; Rocheleau's Great American Industries; 

 Mineral Resources of the United States, a 

 pamphlet issued by the United States Geological 

 Survey. 



Related Subjects. The reader of the above 

 discussion will find much of interest in ,the fol- 

 lowing articles in these volumes : 

 Carbon Magnetite 



Charcoal Malleability 



Civilization Manganese 



Coke Phosphorus 



Concrete Rolling Mill 



Electromagnet Rust 



Electromagnetism Silicon 



Graphite Slag 



Gravity, Specific Steel 



Hematite Strength of Materials 



Iron Age Sulphur 



Limestone Telegraph 



Magnet and Magnetism Telephone 



IRON AGE, the last of the prehistoric ages, 

 following the ages of bronze and stone. It 

 was the period in the development of civiliza- 

 tion when iron began to be used for tools and 

 weapons. Before the Iron Age all tools were 



made of copper, bronze and ohipped or polished 

 stone; but the ancient peoples somehow dis- 

 covered that iron was harder than bronze, that 

 it would take a sharper edge, and that, since 

 it required no fusing or mixing of metals, it 

 was much easier to work. They also discov- 

 ered that iron beaten or hammered into shape 

 was stronger and less breakable than iron cast 

 into shape, so most implements of the Iron 

 Age are of wrought iron, as hand-hammered 

 iron is called. Many of them were skilfully 

 made and beautifully decorated; some, evi- 

 dently of a later date, have symbols and letters 

 upon them indicating the beginning of writing. 



The peoples of Southern Europe learned how 

 to use iron long before those of the northern 

 countries. The age of Aeneas, Achilles, Helen 

 of Troy and King Menelaus, portrayed by 

 Homer in his Iliad and Odyssey, was the first 

 of the Iron Age, but the people of the Norse 

 lands knew little of iron previous to the time 

 of Caesar, about fifty years before Christ. See 

 IRON. 



IRON CROSS, a German military decora- 

 tion awarded to officers and men of the army 

 and navy for acts 

 of bravery or for 

 dist i ngu i shed 

 service in war. As 

 its name indicates, 

 it is made of iron, 

 and it has there- 

 fore no intrinsic 

 value, while its 

 design, as shown 

 in the illustration, 

 is very simple. 

 This decoration 

 was instituted by 

 King Frederick 

 William III of 

 Prussia in March, 

 1813, at the time 

 of the struggle of 

 Germany against 

 Napoleon. At 

 that time it was 

 given only to 

 Prussians, but when it was revived during the 

 Franco-German War in 1870 it was awarded to 

 any German soldier who deserved to receive it. 

 There are two classes, the first and second, 

 awarded according to the merit of the deed per- 

 formed. 



In simplicity of design, small intrinsic value, 

 and the honor and reward bestowed upon the 



AN IRON CROSS 

 Presented for valor in 1916. 



