But of all the different kinds of iron, the palm of excellence is awarded to that which is made by the Seres,[1674] who send it to us with their tissues and skins;[1675] next to which, in quality, is the Parthian[1676] iron. Indeed, none of the other kinds of iron are made of the pure hard metal, a softer alloy being welded with them all. In our part of the world, a vein of ore is occasionally found to yield a metal of this high quality, as in Noricum[1677] for instance; but, in other cases, it derives its value from the mode of working it, as at Sulmo,[1678] for example, a result owing to the nature of its water, as already stated. It is to be observed also, that in giving an edge to iron, there is a great difference between oil-whetstones and water-whetstones,[1679] the use of oil producing a much finer edge. It is a remarkable fact, that when the ore is fused, the metal becomes liquefied like water, and afterwards acquires a spongy, brittle texture. It is the practice to quench smaller articles made of iron with oil, lest by being hardened in water they should be rendered brittle. Human blood revenges itself upon iron; for if the metal has been once touched by this blood it is much more apt to become rusty. CHAP. 42.—THE METAL CALLED LIVE IRON. We shall speak of the loadstone in its proper place,[1680] and of the sympathy which it has with iron. This is the only metal that acquires the properties of that stone, retaining them for a length of time, and attracting other iron, so that we may sometimes see a whole chain formed of these rings. The lower classes, in their ignorance, call this “live iron,” and the wounds that are made by it are much more severe. This mineral is also found in Cantabria, not in continuous strata, like the genuine loadstone, but in scattered fragments, which they call “bullationes.”[1681] I do not know whether this species of ore is proper also for the fusion of glass,[1682] as no one has hitherto tried it; but it certainly imparts the same property as the magnet to iron. The architect Timochares,[1683] began to erect a vaulted roof of loadstone, in the Temple of Arsinoë,[1684] at Alexandria, in order that the iron statue of that princess might have the appearance of hanging suspended in the air:[1685] his death, however, and that of King Ptolemæus, who had ordered this monument to be erected in honour of his sister, prevented the completion of the project. CHAP. 43. (15.)—METHODS OE PREVENTING RUST. Of all metals, the ores of iron are found in the greatest abundance. In the maritime parts of Cantabria[1686] which are washed by the Ocean, there is a steep and lofty mountain, which, however incredible it may appear, is entirely composed of this metal, as already stated in our description of the parts bordering upon the Ocean.[1687]