Perhaps there is no test which is more conclusive of the state of prehistoric civilization and commerce than that which is afforded by the general knowledge and use of metals. It is true that a knowledge of some of the metals which are found in a native state, or in easily fusible ores, may coexist with very primitive barbarism. Some even of the cannibal tribes of Africa are well acquainted with iron, and know how to smelt its ores and manufacture tools and weapons. Gold also, which is so extensively found in the native state, could not fail to be known from the earliest times; and in certain districts pure copper presents itself as only a peculiar and malleable sort of stone. But when we come to metals which require great knowledge of mining to detect them in their ores, and to produce them in large quantities; and to alloys, which require a long practice of metallurgy to discover, and to mix in the proper proportions, the case is different, and the stone period must be already far behind. Still more is this the case when tools and weapons of such artificial alloys are found in universal use in countries where Nature has provided no metals, and where their presence can only be accounted for by the existence of an international commerce with distant metal-producing countries. Iron was no doubt known at a very early period, but it was extremely scarce, and even as late as Homer's time was so valuable that a lump of it constituted one of the principal prizes at the funeral games of Patroclus. Nor is there any reason to suppose that the art of making from it the best steel, which alone could have competed with bronze in cutting granite and diorite, had been discovered. It may be assumed, therefore, that bronze was the material universally used for the finer tools and weapons by the great civilized empires of Egypt and Chaldæa during the long interval between the neolithic stone age and the later adoption of iron.