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Portland cement differs from natural cement in three ways. First, rather than using naturally mixed raw materials, Portland cement is manufactured with by mixing the limestone and clay materials to achieve specific chemical properties. Second, it is burnt at much higher temperature and requires more powerful mills for grinding. Third, it eventually became stronger than natural cement. Though first patented in 1824 production began on a wide scale in England in the 1860s following its well publicized use in the new sewer system in London.
Production of Portland cement in the United States began in 1871 at Coplay, about a mile south-east from Siegfried, along the Lehigh River, though on the other side of the river in Lehigh County. David O. Saylor and associates began producing natural cement there in 1866, as the Coplay Cement Company. He also began experiments to produce Portland cement and successfully did so, in 1871 being granted a patent for the first American Portland cement. The chemist for the Coplay Cement Co. was John W. Eckert, a recent graduate from Lehigh University, who had done work for the Pennsylvania Geological Survey while a student there. As well as being the first manufacturer, the Coplay Cement Co. was, importantly, one of the most durable manufacturers during the birth of the American industry. Its profitability is demonstrated by its regular investments in new kilns to increase capacity. In 1885, a story in the New York Times about the Coplay Cement Co. predicted that "it is only a matter of time when the importation of foreign cement will become a matter of history".
Other manufacturers of Portland cement (though all also produced natural cement) in the Lehigh Valley followed the Coplay Cement Co. all in Lehigh County around the Coplay Cement Co. The largest of the other entrants was the American Improved Cements Company at nearby Egypt. This was begun by Robert W. Lesley who had previously been a distributer of Coplay Cement. John W. Eckert moved from the Coplay Cement Co. to become the superintendent of this company. Entry also occurred outside of the Lehigh Valley but many of these entrants failed within a few years, either proving unprofitable or, in some cases, burning down and not being rebuilt. The ongoing success of the Coplay Cement Co., American Improved Cements Co. and a very few others, demonstrated, despite the failures, Portland cement could be made in the United States.
