To state the matter in a simple way, iron ore, which is essentially a natural “iron rust,” is the metal, iron, held in the strong chemical grip of the gas, oxygen, which normally forms one-fifth of the air we breathe. As you note, the combination forms a substance entirely unlike either the iron or the oxygen, but both of these can be regenerated from it (the ore) by chemical methods. Under influence of high heat (this is one of the chemical methods, by the way), this stranglehold can be broken by carbon, of which lampblack, graphite, charcoal, and coke, are our most familiar examples. The result, in the small, crude, and inefficient furnaces of long ago was a disappointingly small ball of crude iron, pasty and scarcely meltable, even at highest heats, but soft and malleable when cold. As mentioned, it was a variety of what is now commonly called “wrought iron.” [Illustration: A CATALAN FORGE WITH ITALIAN TROMPE, OR WATER BLOWER ] The ancients got this far. 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.