The history of metal-working begins well before that of the extraction of metals from their ores, for a number of metals, such as gold, occur naturally in their uncombined state. The precious metals probably first attracted man's attention by their glitter and the same quality led to their extensive use for decorative purposes. Of metals useful mainly for strictly practical purposes, iron was literally heavensent, for iron from meteors was greatly prized for tool-making: much more recently, the iron in a meteor that fell in Greenland was utilized by Eskimos for more than a century. Copper was another metal originally known in its elementary state, though deposits of this kind were soon exhausted and extraction from ores became necessary.

The utilization of ores involves two separate processes: first, the separation of the metal from other elements with which it is chemically combined; and second, the working-up of the metal into useful articles. Metallic ores are, in the chemical sense, extremely varied, but in a large number of them the desired metal is combined with sulphur or oxygen. To separate the metal it is necessary to provide an alternative partner for this sulphur, oxygen, or other constituents of the ore. In many instances carbon is most satisfactory for this purpose and, since the chemical reaction usually takes place only at high temperatures, the furnace plays a paramount part in metal extraction processes. Carbon, which within the period we are now considering means almost invariably charcoal, provides both the means for reducing metals to their elementary state and the heat necessary for the reaction to take place. A further consequence of the high temperature is that the metal may be obtained in a molten condition and so can be run off from infusible impurities which remain behind as a slag; sometimes a flux is added to facilitate slag formation.

How such a relatively complicated process was first evolved by primitive man must be a matter for speculation, but there is at least plausibility in the suggestion that the first ore smelted was malachite, a green carbonate of copper. This ore occurs fairly widely in the Middle East, and from at least as early as the fifth millennium B.C. was used as a pigment, especially as a cosmetic for painting the lower eye-lid. Malachite is particularly easily reduced to copper, and if a little of the ore were dropped into a fierce wood fire a bead of copper would result. From such a chance discovery might have arisen the deliberate smelting of malachite and thence of other copper ores.

As regards the working-up of the metal, there were two main possibilities. One, which went back to the very earliest days, when man experimented with finds of pure metal which needed no smelting, was simply to shape the metal with hammer and anvil; at a very early stage it was discovered that hammering hardened the metal, but that if desired it could be made soft again by renewed heating. The other way of shaping the metal for use was to pour it while molten into a mould, giving it a rough shape which could be finished with the hammer. It appears that the ancient practice was to remelt metal for casting rather than to cast it straight from the furnace.

The above description applies to the principal metals and their alloys, except for iron. Of the others it may be appropriate to begin with the preparation of gold and silver, since, although the use of gold in the Near East did not necessarily precede that of copper, it quite frequently occurred in a form pure enough for immediate working. Gold in small quantities was to be found in many parts of the ancient world, such as the Caucasus, where the practice of straining alluvial deposits through wool is believed to be the origin of the legend of the Golden Fleece. Egypt, however, had something like a monopoly of its production --more than a hundred gold-mines in the Nubian desert, and others in the Eastern desert. Silver was the characteristic product not of Egypt but of north-east Asia Minor, the district associated with the Hittites, the name of whose capital was written with the ideograph for silver. Silver and lead were found together in the mineral galena (lead sulphide), which could be converted into a lead-silver alloy by roasting it to get rid of some of the sulphur and then heating it to a higher temperature, which further reduced the sulphur content and caused the alloy to form at the bottom of the furnace: the charcoal fuel prevented reoxidation. Sometimes, too, metallic silver underlay the seams of galena. The silver-lead alloy was melted in a porous clay crucible (the cupel) and a blast of air was blown upon it. The lead was thus oxidized and removed, the completion of the process being indicated by the sudden appearance of a shining button of silver. Cupellation, which was probably introduced about 30002500 B.C., was also employed to refine gold. The impure gold was mixed with lead and fused in the cupel; the lead and impurities were then removed by the air blast.

Silver and gold became standards of value, but weights and bars of copper and lead were used even earlier for the same purpose and continued to be circulated more frequently than the precious metals in actual payments. Copper was the first of the useful metals. Since native copper is rarely found in quantity, although lumps weighing several hundred tons are not unknown, its widespread use presupposes widespread mining, such as occurred in Asia Minor, Armenia, and Elam, from which the Sumerians received it as early as 3500 B.C.; in the island of Cyprus, whence the peoples of Italy imported it and named it cuprum; in the Egyptian centres described in the book of Job; and in many parts of Europe. In the earliest days stone tools were used by the miners; later, bronze ones. The vein of ore was by preference followed horizontally into the rock, occasionally for as much as 50 yds; but relics in Hungary reveal vertical shafts up to 6 ft in diameter, sometimes duplicated to provide ventilation, with access by notched tree-stems and even, in one case, a three-spoked windlass. Miners worked by the pillar-and-stall method, leaving pillars of ore intact to support the roofs of the passages which they cut into the vein. Where rock was a serious obstacle they broke it up by fire-setting, that is, lighting a fire to heat the rock, which could then be splintered by throwing on cold water. Early methods of mining metallic ores doubtless owed much to the practice of flint-miners, who had learnt to work at depths of about 30 to 40 ft.

The extraction of metal from the widely different types of copper ore involved complicated smelting processes. In the eastern Alps, for instance, where some 20,000 tons of copper are believed to have been produced in the period 1300-800 B.C., ore and fuel were piled together for smelting, and after three successive stages of refinement, the copper was still only about 95 per cent. pure. For further purification, it was necessary to melt the copper with charcoal and apply a blast of air.

Although there was apparently a true Copper Age in Egypt up to about 2000 B.C., that is to say, a period during which pure copper was utilized, the history of the use of this metal was from a very early date inextricably linked with that of tin. Copper of such purity as was yielded by ancient processes is a relatively soft metal; certain of its alloys therefore had far greater practical value. Outstanding among these was bronze, the alloy of copper and tin, its precise properties depending on the relative proportions of the two metals. The origin of bronze is uncertain, and may well have been different in different places, but it is reasonable to suppose that it was first discovered by the accidental smelting of mixed ores of copper and tin, such as are known to occur; not until very much later were different species of ore clearly distinguished. Before long, however, copper and tin ores were being deliberately mixed in predetermined proportions by European smelters. . .