The art of casting in metal was also practised by the Sumerians, and even in the earliest period, anterior to the reign of Ur-Ninâ, small foundation-figures have been discovered, which were cast solid in copper. In fact, copper was the metal most commonly employed by the Sumerians, and their stage of culture throughout the long period of their history may be described as a copper age, rather than an age of bronze. It is true that the claim is sometimes put forward, based on very unsatisfactory evidence, that the Sumerian metal-founders used not only tin but also antimony in order to harden copper, and at the same time render it more fusible;[33] and it is difficult to explain the employment of two ideograms for the metal, even in the earlier periods, unless one signified bronze and the other copper.[34] But a careful analysis by M. Berthelot of the numerous metal objects found at Tello, the dates of which can be definitely ascertained, has shown that, even under the later rulers of Lagash and the kings of Ur, not only votive figures, but also tools and weapons of copper, contain no trace of tin employed as an alloy.[35] As at Tello, so at Tell Sifr, the vessels and weapons found by Loftus are of copper, not bronze.[36] The presence of an exceedingly small proportion of elements other than copper in the objects submitted to analysis was probably not intentional, but was due to the necessarily imperfect method of smelting that was employed. [Illustration: CLAY RELIEF STAMPED WITH THE FIGURE OF THE BABYLONIAN HERO GILGAMESH, HOLDING A VASE FROM WHICH TWO STREAMS OF WATER FLOW. _Brit. Mus., No._ 21204.] [Illustration: FRAGMENT OF LIMESTONE SCULPTURED IN RELIEF WITH VASES FROM WHICH STREAMS OF WATER FLOW. _Brit. Mus., No._ 95477]