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,[1] 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 a 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;[2] and another which is more particularly liable to rust. All these varieties are known by the name of "strictura,"[3] 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.[4] 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,[5] for example, and Turiasso[6] in Spain, and Comum[7] 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,[8]who send it to us with their tissues and skins;[9] next to which, in quality, is the Parthian[10] 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[11] for instance; but, in other cases, it derives its value from the mode of working it, as at Sulmo,[12] 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,[13] 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.

1. The Isle of Elba, which has been celebrated for the extent and the richness of its iron mines both by the ancients and the moderns.—B. Ajasson remarks that it appears to be a solid rock composed of peroxide of iron.

2. " Clavis caligariis." See B. viii. c. 44, B. ix. c. 33, and B. xxii. c. 46.

3. There have been numerous opinions on the meaning of this word, and its signification is very doubtful. Beckmann has the following remarks in reference to this passage:—"In my opinion, this was the name given to pieces of steel completely manufactured and brought to that state which rendered them fit for commerce. At present steel comes from Biscay in cakes, from other places in bars, and both these were formerly called 'stricturæ,' because they were employed chiefly for giving sharpness to instruments, or tools, that is, for steeling them. In speaking of other metals, Pliny says that the finished productions at the works were not called 'stricturæ' (the case, for example, with copper), though sharpness could be given to instruments with other metals also. The words of Pliny just quoted are read different ways, and still remain obscure. I conjecture that he meant to say, that some steel-works produced things which were entirely of steel, and that others were employed only in steeling—'ad densandas incudes malleorumve rostra.' I shall here remark that these 'stricturæ ferri' remind us of the ' striges auri,' (see B. xxxiii. c. 19), such being the name given to native pieces of gold, which, without being smelted, were used in commerce."—Hist. Inv. Vol. II. p. 327. Bohn's Edition.

4. " A stringenda acie." The iron was probably formed into thin, long bars, in thickness resembling a steel used for sharpening. The French word acier, meaning "steel," may possibly come from the Latin " acies"—" edge," as Beckmann has suggested.

5. Situate at the spot now known as "Bambola," near Calatayud. The river Salo ran near it, the waters of which, as here mentioned, were celebrated for their power of tempering steel. The poet Martial was a native of this place.

6. Supposed to be the modern Tarragona.

7. See B. iii. c. 21.

8. See B. vi. cc. 20-24, B. vii. c. 2, and B. xii. cc. 1, 41. This Seric iron has not been identified. Ctesias, as quoted by Photius, mentions Indian iron. See Beckmann, Vol. II. p. 228. Bohn's Edition.

9. Thought by Beckmann, quoting from Bottiger, possibly to bear reference to a transfer trade of furs, through Serica, from the North of Asia. See Vol. II. p. 307. As to the Seric tisssues, see B. xxxvii. c. 77.

10. Or "Persian." The steel of Damascus had in the middle ages a high reputation.

11. See B. iii. cc. 24, 27. Horace speaks of the "Norican sword" on two occasions.—B.

12. See B. iii. cc. 9, 17.

13. See B. xviii. c. 67, and B. xxxvi. c. 38.