Copper seems to have been the first of all the metals to attract the notice of man, and to be manufactured by him. This is to be accounted for partly by the frequency of its occurrence in its native state, partly by the fact that it can be smelted at a comparatively low temperature. Soft and ductile, copper has rendered many services to man from a very early period, and, both in Chaldæa and the Nile valley, he very soon learnt to add greatly to its hardness by mixing a certain quantity of tin with it. Where did the latter material come from? This question we can no more answer in the case of Mesopotamia than in that of Egypt; no deposits of tin have yet been discovered in the mountain chains of Kurdistan or Armenia.[375] However this may be, the use of tin, and the knowledge of its properties as an alloy with copper, dates from a very remote period in the history of civilization. In its natural state, tin is always found in combination, but the ore which contains it in the form of an oxide does not look like ordinary rock; it is black and very dense; as soon as attention was turned to such things it must have been noticed, and no great heat was required to make it yield the metal it contained. We do not know where the first experiments were made. The uses of pure tin are very limited, and we cannot even guess how the remarkable discovery was made that its addition in very small quantities to copper would give the precious metal that we call bronze. In the sepulchral furniture with which the oldest of the Chaldæan tombs were filled we already find more bronze than pure copper.[376] Lead is rare. A jar of that metal, and the fragment of a pipe dug up by Loftus at Mugheir may be mentioned.[377] It is curious that iron though still far from common, was not unknown. Iron nowhere exists in its native state on the surface of our planet, except in aerolites. Its discovery and elimination from the ore requires more time and effort and a far higher temperature than copper or tin. Those difficulties had already been surmounted, but the smelting of iron ore was still such a tedious operation that bronze was in much more common use. Iron was looked upon as a precious metal; neither arms, nor utensils, nor tools of any kind were made of it; it was employed almost exclusively for personal ornaments, such as rings and bracelets.[378] Gold, which is found pure in the veins of certain rocks and in the beds of mountain torrents, and in pieces of a size varying from that of a grain of dust to nuggets of many pounds, must very soon have attracted the attention of man, and excited his curiosity, by its colour and brilliancy. We find it in the tombs mixed with objects of stone and bronze. Round beads for necklaces, earrings and finger rings of not inelegant design were made of it. [Illustration: FIG. 192.--Iron mattock; from Place.]