CHAPTER XXin. OPEN-HEARTH PROCESS.
In 1868 the manufacture of acid open-hearth steel com¬ menced. The Siemens regenerating furnace was used, and the Martin system, generaUy known as the Siemens-Mar¬ tin process. But its progress was slow, as it foUowed the Bessemer, wliich was spectacular, beautiful, exciting, and most intensely interesting in the blowing of a heat of metal. Whfle the Siemens-Martin process is scientific and simple, it is not so interesting and exciting as the Bessemer process, and it did not command the attention and respect to which it was entitled. The fact that the Bessemer had been introduced and the machinery in use, and the knowledge gained in the use of refractory material and in the handling of steel, made the introduction of the open-hearth process easy as compared with the Bessemer. But the fact that it so modestly made its way into general use does not in any way detract from its great usefulness, and with the later introduction of the Thomas and Gilchrist basic process and its appUcation to the Siemens furnace, the basic open- hearth process takes rank as the greatest metallurgical discovery of the age.
Taking into consideration the character of our ores and coal, and their geographical location, its unportance at once becomes manifest. It is the most important and valuable invention that has yet been made in the Une of metaUurgy. The ores that can be used in the basic open-hearth process are known to exist in almost every state in the Union, while