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4 into shape. Thus, for instance, the North American Indians obtained pure copper from the mines near Lake Superior and elsewhere, and hammered it at once into axes, bracelets, and other objects.

Tin also early attracted notice, probably on account of its great heaviness. When metals were very scarce, it would naturally sometimes happen that, in order to make up the necessary quantity, some tin would be added to copper, or vice versâ. It would then be found that the properties of the alloy were quite different from those of either metal, and a very few experiments would determine the most advantageous proportion, which for axes and other cutting instruments is about nine parts of copper to one of tin. No implements or weapons of tin have yet been found, and those of copper are rare, in Western Europe, whence it has been inferred that the art of making bronze was known elsewhere before the use of either copper or tin was introduced into Europe. Many of the so-called "copper" axes, etc., contain a small proportion of tin; and the few exceptions indicate probably a mere temporary want, rather than a total ignorance, of this metal.

The ores of iron, though more abundant, are much less striking in appearance than those of copper. Moreover, though they are perhaps more easily reduced, the metal, when obtained, is much less tractable than bronze. This valuable alloy can very easily be cast, and, in fact, all the weapons and implements made of it in olden times were cast in moulds of sand or stone. The art of casting iron, on the other hand, was unknown until a compara- tively late period.

In the writings of the early poets, iron is frequently characterized by the epithet, and its adjective, , is used metaphorically to imply the greatest stubbornness.

These considerations tend very much to remove the a priori improbability that a compound and comparatively expensive material like bronze should have been in general use before such a common metal as iron, and the evidence that it was so seems conclusive.