Why New Discoveries May be a Disadvantage.—The same trouble will probably reappear in the future, for geographical dis covery and the improvement of mining processes and transportation have by no means reached their limits.* Western China, Tibet, Afghanistan, and especially northeastern Siberia contain vast amounts of gold, which will be exploited when railroads bring those regions into close contact with the rest of the world. In South Africa the Witwaters field alone is believed to contain from ten to twenty billion dollars' worth of gold. The increased production of gold benefits a few people, but for the majority it merely helps increase the cost of living. In this it joins with short hours, poor work, heavy taxes, and the effects of war. So much trouble arises from changes in the valtie of gold that many economists think it should be given up as the standard of value. They advocate a new standard based on goods of all kinds and so framed that a dollar will buy just as much food, cloth, iron, coal, or other necessities in one year as in another.
Remarkable Nature of Iron.—If all the gold in the world should be destroyed man's activity would go on almost unchanged, but if iron should be taken away, it would be enormously more difficult than at present to maintain our material civilization.
Why is iron used so universally? - Is it because iron is the most common metal? No, for the earth's crust contains about 8.2 parts of aluminum out of a hundred, and only 4.6 of iron. Moreover, such metals as calcium. (3.5 parts), magnesium (2.6 parts), sodium (2.6 parts) and potassium (2.4 parts), are only a little less abundant than iron, but are not used one-thousandth as much. Is the universal use of iron due to the ease with which the metal can be separated from its ores? Partly, but copper can be separated still more easily, and zinc with almost equal ease.
The chief reason for the universal use of iron is its peculiar prop erties, especially (1) its capacity for assuming many different forms, (2) its strength, (3) its hardness, (4) its ductility or capacity for being drawn into wire, and (5) its magnetic properties. Because of these qualities iron is the universal material for tools and machines, and thus becomes one of the most important factors in promoting civilization.
How Man Has Attained the Iron Age.—Since iron is so important it is not strange that the period in which we live is known as the Iron Age. The earliest men lived in what is known as the Stone Age. Their only tools were made of stone or sometimes of bone, Ordinary stones of almost any kind were used for hammers or as weapons to throw when hunting game, but only flint and a volcanic glass called "obsidian" could be easily chipped to a cutting edge. But what is such an edge compared with the edge of a razor. Peo ple with such tools are greatly hampered in the advance toward civilization.
When primitive people discovered that copper could readily be hammered into tools, the Copper Age began. It was not greatly different from the Stone Age, however, for copper is so soft and pliable that tools made from it can never be given an edge that will last. In time it was discovered that if a little tin is melted with copper a material called bronze is produced. This is harder than copper and makes better tools. This discovery gave rise to the Bronze Age. The new metal' helped mankind to advance, but it did not surpass copper sufficiently to cause a pronounced change in civilization.
Not till men learned to smelt iron did there come a radical change. Since then, during the two or thtee thousand years of the Iron Age, the strength and hardness of iron tools have enabled us to clear the forests, plow the sod, dig deep mines, and construct railroads, steam ships, and all kinds of machinery. Within the last half century the increasing use of iron in its strongest and hardest form has brought us into the Steel Age, a new stage of the Iron Age. In 1870 the United States produced 1,665,000 tons of pig iron, only 4 per cent of which, or about 70,000 tons, was used for steel. In 1900 the output of steel had increased to 10,000,000 tons, in 1905 to 20,000,000, in 1913 to 32,000,000, and in 1918, at the climax of the Great War, to 50,000,000.
The utilization of the magnetic properties of iron has enabled man to enter upon a still more advanced stage of the Iron Age, the Age of Electricity. As lately as the early part of the last century the only practical use of the electromagnetic power of iron was in the compass. To-day we depend upon electricity not only for lighting, transportation, and communication, but also for the transmission of power from waterfalls, for motive power in factories, and for a host of other uses. Even now the full possibilities of the magnetic prop erties of iron are only beginning to be realized.
Scanty Iron Deposits and the Character of Early Civilization.— One of the chief reasons for the differences between the ancient civi lization of Egypt, Palestine, Mesopotamia, Greece, and Rome, on the one hand, and the modern civilization of Western Europe and the United States, on the other, is the amount of iron available for everyday use. In phases of civilization such as art, literature, philosophy, religion, and government, in which mineral resources play only a small part, the people of ancient times made great prog ress, and in many ways excelled the nations of to-day. In other phases such as manufacturing, transportation, commerce, and min ing, where complex machinery plays an important part, they made little progress and were in about the same stage as nations like modern China. This difference was due largely to the degree of availability of supplies of iron (see Fig. 53).