Edison: His Life and Inventions by Frank Lewis Dyer and Thomas Commerford Martin

EDISON PORTLAND CEMENT NEW developments in recent years have been more striking than the general adoption of cement for structural purposes of all kinds in the United States; or than the increase in its manufacture here. As a material for the construction of office buildings, factories, and dwellings, it has lately enjoyed an extraordinary vogue; yet every indication is confirmatory of the belief that such use has barely begun. Various reasons may be cited, such as the growing scarcity of wood, once the favorite building material in many parts of the country, and the increasing dearness of brick and stone. The fact remains, indisputable, and demonstrated flatly by the statistics of production. In 1902 the American output of cement was placed at about 21,000,000 barrels, valued at over $17,000,000. In 1907 the production is given as nearly 49,000,000 barrels. Here then is an industry that doubled in five years. The average rate of industrial growth in the United States is 10 per cent. a year, or doubling every ten years. It is a singular fact that electricity also so far exceeds the normal rate as to double in value and quantity of output and investment every five years. There is perhaps more than ordinary coincidence in the association of Edison with two such active departments of progress. As a purely manufacturing business the general cement industry is one of even remote antiquity, and if Edison had entered into it merely as a commercial enterprise by following paths already so well trodden, the fact would hardly have been worthy of even passing notice. It is not in his nature, however, to follow a beaten track except in regard to the recognition of basic principles; so that while the manufacture of Edison Portland cement embraces the main essentials and familiar processes of cement-making, such as crushing, drying, mixing, roasting, and grinding, his versatility and originality, as exemplified in the conception and