Speaking in terms of the power house, it is also the “Age of Cast Steel.” Twenty-five years ago the manufacturer and power house man were quite content with their “saturated” steam temperatures and pressures. With cast iron valves and fittings their plants were well equipped. [Illustration: STEEL CASTINGS SHOWING THE RISERS ON THE FLANGES Castings for use on steam, ammonia, water lines, etc., must be of very close-grained metal and require much larger risers than castings for less exacting service. ] But the world did not stand still. It became known that by heating the steam out of contact with the water in the boiler it lost the moisture which it carried and became dry and then could be charged with as much additional heat as it was desired to give to it. This “superheated” steam, of course, would do more work and it had also certain other advantages which the old-fashioned “saturated” steam had not. But while cast iron fittings gave satisfactory service up to temperatures, say, around 450° F., they faltered when forced to work under the new conditions which meant decidedly higher temperatures and pressures. And, too, the repeated heatings and coolings which were often necessary, disclosed a disadvantage previously unknown—a so-called “permanent growth” of the cast iron which was attended by loss of strength, and altogether it was soon found out that when superheated steam was to be used, higher types of materials were advisable than those which had been used under old conditions. [Illustration: STEEL CASTINGS IN THE ANNEALING OVEN ] Superheated steam has rapidly come into general use. Some of the new locomotives and most of the modern power plants are now built for as much as 200° superheat, i.e., a total temperature of approximately 600° Fahrenheit. Valves and fittings of cast steel not only are the articles “de luxe” for such service but they have come to be considered the necessary articles and their advantages have only fairly begun to be appreciated. Though our most august scientific societies are proposing and debating upon systems of classification which shall include and satisfactorily define all of our ferrous metals, a satisfactory one has not yet been evolved, and, considering the intricacy of our ferrous metallurgy and the discoveries which are being made almost daily, the outlook for a strictly logical classification is not yet flattering. With “Cast Steel” our metallurgical nomenclature is again faulty. Before what we now call the “steel casting” was known, crucible steel was poured into ingots, “forged” into tools just as it now is and often went under the name “Cast Steel” to distinguish it from the contemporaneous material, wrought iron. So to-day we buy many tools and implements which bear the name cast steel, which we know to have been forged in bringing them into their final shape.