Coke, the fuel used to make steel, is obtained, as is probably universally known, from coal. In the old days of the trade, and to a great extent still, the coal was burned in brick ovens with open tops, known as bee-hive ovens, which produced about sixty tons of coke from each 100 tons of coal and blew out in smoke into the air the oils and gas contained in the coal. Even to-day, in the great coal fields that lie near Pittsburgh, may still be seen the dense smudge that arises in the air from thousands of these ovens. But their day is surely, if slowly, passing. In the modern by-product coke ovens sixty-five to eighty tons of coke are obtained from 100 tons of coal, a gain of nearly 25 per cent. in the case of low volatile and about 8 per cent. with high volatile coals. Nor is this saving all. The gases with their oil content instead of being blown out into the air and burned are conducted through pipes to an intricate apparatus where coal tar, ammonium sulphate, a valuable fertilizing agent, ammonia, and benzol, an important base for high explosives and dyes and also usable as fuel for motor cars, as well as other products are extracted, and the gas itself is made available for use in motor engines or in illuminating. More than one city to-day lights its street with the gas from by-product coke plants. As it requires more than one ton of coke to make a ton of steel it is plain that the 25 per cent. saving in the amount of coke obtained from coal by use of the modern by-product ovens means an enormous economy to the Corporation which produces from seventeen to twenty millions of tons of steel a year, and the saving of four to five millions of tons of coal to the country. Nor are the profits derived from the sale of the by-products themselves immaterial. How profitable is the manufacture of coke by-products is indicated by the fact that for years before the World War, and possibly even to-day, the patentees of one by-product process were usually willing to erect a plant in connection with a steel plant, at a cost of several millions, and to take their pay for it from the profits of the by-products alone, handing the plant over to the steel company at the end of a stated period. They said in effect: “You give us the coal and we will hand you over the coke produced from it; and in twenty years we will give you the plant.” The Corporation, however, has always erected its by-product coke plants at its own expense. Another important economy in its saving of both labor and material is found in the generation, from what were formerly the waste gases of blast furnace operations, of electric power for running the entire steel mill.