Hall's first jobs were in engineering. In 1887 he became a manager with a small steel plant in southern Ohio. Later he took a position as a manager of a steel plant in Belleville, Illinois. In the early 1890s it was discovered that Alexandria, Indiana, had a large supply of natural gas. The steel plant wanted to take advantage of this cheap fuel, so sent Hall to that city to investigate the possibilities of operating a steel mill plant there. He started the disassembly of the Belleville plant in 1895 and reconstructed it in Alexandria. Hall moved with his family to Alexandria permanently in 1897. The plans of operating this plant in this city fell through when it merged with Republic Steel Company in 1898 and moved to Youngstown, Ohio. Hall was on a business trip in Pittsburgh in 1897 and saw mineral wool being made from steel slag. Some of the drawbacks he noted were that it soon disintegrated into powder and was unstable when moist. He thought that perhaps Alexandria's abundance of limestone to make a rock wool product similar to the steel mineral wool might be something to work on. Hall, using his chemical engineering background, experimented with the bedrock material. He discovered that it had a melting point near that of glass. He played with this molten stone in steel cupola furnaces and drew fibers out of them with blasts of air. The result of this experiment was a wool-like substance similar to that of the steel slag mineral wool. His product however did not have sulfur in it, which he considered caused the problems with steel mineral wool. He eventually determined that his material was an excellent insulator. He organized some investors and with $600 started a plant in 1897 to produce this insulating material in Alexandria. Hall negotiated the purchase on several hundred acres of land that contained limestone that could be used in the future for making rock wool. At the time he was manufacturing this insulating material, the chief users of insulation were breweries, distilleries, and cold storage facilities. For their insulation they used cork that was imported from Spain and Portugal. These firms were skeptical of Hall's new insulating material, so he made board-like sheets under the brand name "Rock Cork" to make it more appealing to the market. Hall in 1902 created the Chemical Crystal Company to produce this product as the first factory in the United States to do so. A few years later the natural gas supply of the area had been used up. All the local industries moved out, including the original investors of Chemical Crystal Company and the company ceased to exist. Hall then organized in 1906 another group of investors for the Banner Rock Company. It operated the same plant in Alexandria. They used coke then as a substitute fuel for the furnaces to melt the rock to product the rock wool material. By the 1920s the business was very productive. Hall then acquired additional lots in Alexandria for building. A second plant was eventually built and later two additional plants. Hall initiated the rock wool insulation industry in America. He is considered its father and progenitor.
Hall sold Banner Rock Company in 1929 to Johns-Manville Corporation and retired. He bought a roofing company in his retirement, which he ran to the end of his life. Hall died August 19, 1935.
Works
The Storage of Coal: Its Feasibility and Advantages
