But this was not “cast iron.” When, however, much more charcoal was present in the highly heated furnace than was necessary simply to combine with the oxygen of the ore, the liberated iron greedily absorbed enough of the extra carbon to change its own nature. The metal then became very fluid, whereas before it had been pasty and stiff even at much higher temperatures, or, indeed, at white heat. This liquid iron could be “cast,” that is, poured into molds and in that way made into various useful shapes. It therefore became known as “cast iron” because of this property.
So the brittle metal (cast iron) in our kitchen ranges, for instance, is only the early malleable form of the metal surcharged with or having a large amount of carbon (3½ per cent to 5 per cent) in its make-up, and it is this supercarbon content which confers the fluid quality while hot and the extreme brittleness when cold. True, there are other important constituents in our modern cast iron, but for our present purpose they need not be dealt with.
It has been stated that the ancients got only as far as balls of wrought iron. They really got further as their very fine sword steels show—the “Wootz” of India, the “Damascus” of Syria, and later the “Toledo” of Spain. These they produced by heating rich ore in very small, closed crucibles with just enough carbon (pieces of wood or green leaves) to make what we now call “carbon tool steel.” As carbon steel is simply iron which has absorbed not over 2 per cent of carbon (cast iron described above has a supersaturation with its 3½ per cent to 5 per cent of carbon and therefore is entirely different) they were able to make it in small quantities. When hardened by cooling quickly in water, a forged-out blade of this product would cleave without dulling its edge a piece of iron, it is said, or cut cleanly a tuft of silk floss tossed into the air. These steels attained well deserved renown.
While no one can desire to cast the slightest disparagement on the product of that period, much of which was excellent, astonishingly so considering the period, a moment’s consideration will convince one that modern products not only do not suffer in comparison but in reality are immensely superior. The ancients had little or no knowledge of the reason for the proper qualities of their tools and they made the metal from variable materials in a crude way in such small quantities that little uniformity was possible. While some of the product was undoubtedly excellent, much must have been less desirable.
Modern discoveries and inventions, with the great mechanical progress of the last three centuries and the scarcely half-century-old application of chemical control, have given during recent years products of great uniformity and marvelous quality. What can compare with thirty thousand pound lots of steel turned out from one Bessemer converter each seventeen minutes during the 24 hours in the day, that is, a total of 1300 tons or 2,600,000 pounds, in which not only the main controlling element, carbon, but also four lesser ones, silicon, manganese, sulphur, and phosphorus, are held within extremely narrow limits; or the modern blast furnace which produces a million pounds each 24 hours, run with the same certainty of control? Modern high-speed steels which are every day being made have such high quality that tools formed from them will stand up for hours working red-hot under a lathe speed of two or three hundred linear feet per minute taking a deep cut and “plowing out” chips faster than a laborer can carry them away.
The German Stuckofen
Modern war armament which has recently been so well advertised is sufficient answer as to whether modern metallurgy is in advance of that of centuries ago.
The only necessity for such comparisons is that it seems to be a failing of many to think that our forefathers were more wise and better in other ways than we. It was but a few years ago that the fallacious announcement was made that during archeological excavations in Egypt there had been found a fully equipped telephone system. The inference intended to be conveyed, of course, was that Bell’s invention of the telephone had been antedated many hundreds of years.
