Though technical information and statistics are not to be inflicted upon our readers to any extent in this series of articles, it may not be amiss to give one table of interesting figures which show the increase in height and capacity of furnaces from 1850 to the present time. During this period the annual production of pig iron in the United States has risen from 565,000 to 31,000,000 long tons (2240 pounds). It will be noted that since 1887, when we passed Great Britain, the United States has been the champion pig iron producer of the world. The record production of a single blast furnace to date was that of one of the United States Steel Corporation’s furnaces at Duquesne, Penn., which produced 900 tons of pig iron in one day. CHAPTER V A GENERAL GLIMPSE AHEAD We have arrived at the parting of the ways. From the vast beds of iron ore, the coal fields and coke ovens, and from the quarries of limestone, all roads have led to the blast furnace. This we have visited and we now know how pig iron is made. From this point the several paths diverge. One by one we are to follow them to get acquainted with the interesting country which they traverse and the regions to which they lead. However, before choosing any one of these paths for our first trip, it will be to our advantage to pause, to study for a moment our position and get a general view of the country ahead of us. We should know the relative locations and importance of the places we are going to visit, for only by getting a comprehensive idea of the general plan of this ferrous (meaning iron) world, can we understand to the best advantage the position of each of the main products, wrought iron, steel, cast iron, malleable iron, etc., and acquire a satisfactory knowledge of them. In the last chapter pig iron was called the intermediate stage between the ore and the finished iron product, and such the sketch given shows it to be. It is only as an intermediate product that pig iron has value, for nowhere in the commercial world has it a purpose except as a material to be chemically and structurally transformed into other materials which may themselves be used without further transformation. It is desirable that we fully realize the position of this very important semi-raw material, pig iron, before passing on to the study, one at a time, of the refined ferrous products which _are_ susceptible of _direct use_ in our commercial life. [Illustration: ELECTRIC ARC, MICROSCOPE, AND CAMERA, PART OF METALLOGRAPHIC APPARATUS ] From Table A (page 71) it will be seen that from blast furnace metal several well-known products are formed by the various processes of refinement. Each of these methods of purification may be said to result in a certain general composition and structure which give to the material formed its character and properties. The Metallographic Method of Classification