Still, however, human industry has not failed to employ iron for perpetuating the honours of more civilized life. The artist Aristonidas, wishing to express the fury of Athamas subsiding into repentance, after he had thrown his son Learchus from the rock,[1664] blended copper and iron, in order that the blush of shame might be more exactly expressed, by the rust of the iron making its appearance through the shining substance of the copper; a statue which still exists at Rhodes. There is also, in the same city, a Hercules of iron, executed by Alcon,[1665] the endurance displayed in his labours by the god having suggested the idea. We see too, at Rome, cups of iron consecrated in the Temple of Mars the Avenger.[1666] Nature, in conformity with her usual benevolence, has limited the power of iron, by inflicting upon it the punishment of rust; and has thus displayed her usual foresight in rendering nothing in existence more perishable, than the substance which brings the greatest dangers upon perishable mortality.
CHAP. 41.—THE DIFFERENT KINDS OF IRON, AND THE MODE OF TEMPERING IT.
Iron ores are to be found almost everywhere; for they exist even in the Italian island of Ilva,[1667] being easily distinguished by the ferruginous colour of the earth. The method of working the ore is the same as that employed in the case of copper. In Cappadocia, however, it is peculiarly questionable whether this metal is present due to the water or to the earth; because, when the latter has been saturated with the water of a certain river, it yields, and then only, an iron that may be obtained by smelting.
There are numerous varieties of iron ore; the chief causes of which arise from differences in the soil and in the climate. Some earths produce a metal that is soft, and nearly akin to lead; others an iron that is brittle and coppery, the use of which must be particularly avoided in making wheels or nails, the former kind being better for these purposes. There is another kind, again, which is only esteemed when cut into short lengths, and is used for making hobnails;[1668] and another which is more particularly liable to rust. All these varieties are known by the name of “strictura,”[1669] an appellation which is not used with reference to the other metals, and is derived from the steel that is used for giving an edge.[1670] There is a great difference, too, in the smelting; some kinds producing knurrs of metal, which are especially adapted for hardening into steel, or else, prepared in another manner, for making thick anvils or heads of hammers. But the main difference results from the quality of the water into which the red-hot metal is plunged from time to time. The water, which is in some places better for this purpose than in others, has quite ennobled some localities for the excellence of their iron, Bilbilis,[1671] for example, and Turiasso[1672] in Spain, and Comum[1673] in Italy; and this, although there are no iron mines in these spots.
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]
Iron which has been acted upon by fire is spoiled, unless it is forged with the hammer. It is not in a fit state for being hammered when it is red-hot, nor, indeed, until it has begun to assume a white heat. By sprinkling vinegar or alum upon it, it acquires the appearance of copper. It is protected from rust by an application of ceruse, gypsum, and tar; a property of iron known by the Greeks as “antipathia.”[1688] Some pretend, too, that this may be ensured by the performance of certain religious ceremonies, and that there is in existence at the city of Zeugma,[1689] upon the Euphrates, an iron chain, by means of which Alexander the Great constructed a bridge across the river; the links of which that have been replaced are attacked with rust, while the original links are totally exempt from it.[1690]