Malleable iron from which the carbon has not been removed can be hardened and given a steely fracture by sudden cooling from a red heat even if it has previously been annealed. Decarbonized malleable iron, also, can readily be recarbonized by the cementation process. These characteristics are often taken advantage of for the manufacture of tools from malleable iron. Hammers, wood working chisels, gears, etc., are quite largely made. Where they are sold at a cheaper price than the better steel tools and without misrepresentation, there can be little objection, but sometimes they pass for steel. Ofttimes malleable iron castings are made in what are known as “permanent molds” of iron. They are really “chilled castings.” Annealing of these is accomplished in the regular way. Such castings have very smooth and beautiful surfaces but as the iron molds have high first cost they can be used only for castings for which the sales warrant the expense. While much less malleable than is wrought iron or mild steel, annealed malleable cast iron has considerable malleability. It will resist great shock and can be severely battered and bent without breaking. It has about 75 per cent or more of the tensile strength of mild steel and because of the cheapness of its castings the malleable iron industry has developed wonderfully. About a million tons of this product are produced here each year. Naturally malleable iron castings are used where a material with properties intermediate between cast iron and steel will suffice. Such are castings for railroad cars, for reapers, binders, and other agricultural machines, pipe fittings, and the cheaper grades of tools. CHAPTER XIII CAST STEEL We have seen how primitive man hunted and fought with no implements and weapons better than clubs, bows and arrows, and stone hatchets, and how his wife cracked and ground the corn between flat rocks or in mortars of stone. In the succeeding “Bronze Age” we found ornaments, idols and tools being made of copper or the copper alloy, bronze. It was only after the next great advance that we found man utilizing iron for his purposes of civilization. This metal, which with us is so common, was in those days very expensive, so much so that it could be used only for purposes of war and as the gifts of kings. But the world was traveling fast and it was not long before the iron-carbon alloy, steel, was produced. Even so, many hundreds of years elapsed before the present wonderful age was ushered in through the great inventions of Henry Bessemer and the Siemens brothers. And while fine steels for swords and tools have had an incalculably great influence upon the development of the human race, it was the mammoth production of Bessemer and open-hearth steel which permitted its general use as a material for construction of ships, bridges, buildings, and for railroads, that made this the “Age of Steel.”