By the year 1000 B.C., the technology for making bronze, brass, and other copper alloys was quite well understood by all civilizations and even most primitive societies in Europe, Asia, and North Africa. The temperatures of 1300 to 1400 degrees Fahrenheit were by then easily attained in copper smelters and pottery kilns. With iron, it was a totally different story. Iron requires temperatures of about 3000 degrees Fahrebheit to properly separate it from its ores and obtain metal in liquid form that can be cast into molds. It was only in the Middle Ages that Europeans learned to achieve these kinds of temperatures in their iron smelting furnaces. If the high temperatures required weren't enough of a challenge, the handling of iron once it has been heated to high temperatures is quite tricky. It wants to combine with any available oxygen in the fiercest way and will burn brightly at temperatures lower tnan those required to melt it. Early metalsmiths discovered that an impure form of spongy iron could be extracted from its ore if the ore were heated in the presence of plenty of charcoal with air forced through the burning mixture in a sealed furnace. The charcoal burned very hotly and, at the same time, kept all available oxygen away from the iron by using it to keep up its own fire.
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