Soon the metal begins to “come to nature” and little lumps of pure iron here and there through the bath stiffen up into little pasty balls. Some may be seen sticking out through the cinder covering of the bath and others must be torn loose from the bottom with the rabbler. This “balling” period lasts from fifteen to twenty minutes, during which time all of the iron has “come to nature.” [Illustration: THE COAL PILE AND FIRE BOX OF A REVERBERATORY FURNACE ] [Illustration: TURNING THE PIGS TO INSURE EVEN MELTING ] The puddler quickly separates into two or three white-hot balls the 400 pounds or so of spongy iron. These balls, full of and dripping with cinder, are seized, one at a time, with long tongs, removed from the furnace and rushed to the rotary squeezer through which they are twisted and turned, ever becoming longer and smaller in diameter until they emerge from the other and narrower side much compacted and with but little of the cinder which they originally carried. Without being given time to cool, the blooms are seized and shoved into the “muck rolls,” whence after a few passes they emerge as long flat bars, very rough and imperfect in appearance. After shearing into short lengths, many pieces of this “muck bar,” as it is called, are made into “box piles” and tied together with wires. These are charged into the furnace of the finishing mill. After coming to a white heat the box piles go to the finishing rolls where they are rolled into bars, rods, plates, or other shapes desired. By repeated cutting, piling, heating, and rolling, double refined and other high grades of wrought iron are made, each repiling and rerolling, of course, producing a more compact and better product. [Illustration: PUDDLING THE MELTED CHARGE ] [Illustration: CONSIDERABLE CINDER OVERFLOWS DURING THE “BOILING” STAGE ] Wrought iron has a “fiber,” as may be seen from two of the illustrations presented. In “coming to nature” small particles of iron crystallize out as they become purer. These measure perhaps ¹⁄₃₂″ or ¹⁄₁₆″ in diameter. As it goes to the squeezer the ball of “sponge” is made up of such grains of iron loosely welded together with the interstices filled with cinder. The squeezer, and later the rolls, elongate the particles of iron into threads, which, welded together, make the bar. It is thought by some that films of cinder, too thin to be seen under the microscope, surround each fiber of iron and that these afford protection from rusting and give to wrought iron the excellent welding quality that it possesses. [Illustration: DRAWING ONE OF THE BALLS FROM THE FURNACE ] [Illustration: ON THE WAY TO THE “SQUEEZER” ] Steel has no fiber and for this reason it cannot be split as was the wrought iron bar shown in the illustration of page 92.