Page:Popular Science Monthly Volume 25.djvu/96

88 stony ores. The myths of different nations generally indicate a god or a hero as the inventor of metallurgy; but it is now hardly doubtful that this god was in most cases a human mind directed by some accident.

Tin, iron, and the other metals, as we have said, do not occur pure, but as oxides in stone. They have a strong affinity for oxygen, and can not be separated from it and produced in a metallic condition, except by the aid of powerful reagents. There is one element which has a stronger affinity for oxygen than any metal—glowing charcoal, which, in the contest with the metallic oxide, wrests the oxygen from it. In the innumerable places where the primitive man—hunter, fisher, or nomad—built his fires, there can not have failed to be some where the red-hot coals would lie upon a soil containing ores. This would be sufficient to reveal the metallic treasure. By the occurrence of accidents of this kind, men learned to recognize the metal, and in a similar way how to extract it from the earth.

Of the two hard metals we have named, bronze came earlier into use, while the fabrication of iron belongs to a later period of civilization. It has been thought strange that bronze, a compound of two constituents, should have been got and used earlier than the simple metal, iron. And it has been objected that the former product is generally too soft to be valuable for weapons and tools, that pure copper is hard to get, and that tin-ore occurs in only a few places. All of these objections must yield to historical facts; and they can not be upheld against opposing geological considerations. First, it is not true that an alloy is harder to produce than a single metal. Man must in the beginning have melted up together the ores of different kinds as they occurred associated in nature, and thus have obtained a variety of alloys. Among others, copper and tin ores occur near each other in several regions. In such places bronze would have been produced, at first accidentally, afterward on purpose. In other places, where these metals are not naturally associated, one or the other of the constituents, or perhaps the alloy already formed, had to be imported. The second objection is no less fallacious: if substances containing phosphorus are melted up with the ores, the resultant product will have considerable hardness, which may be increased by repeated tempering and hammering. The third objection rests on observations in the most famous copper districts of Europe. It must be remembered in respect to the mines of these regions, that the operations have been carried on for a long time at a great depth, where the sulphurous copper-ores are, it is true, very hard to utilize. But in former times the ores lay nearer to the surface, and they were, in the degree that they were exposed, purified and made more reducible by atmospheric agencies. Oxides, carbonates, and pure copper were to be found. They were easy to smelt, and gave a pure product. It must also be remembered that tin was not so scarce in the earliest times as it is now; and there are still