Because of their malleability and relative ease of working, copper and lead became synonymous with the complexities of Gothic architecture. Endowed with the rich green patina of age, weathered copper spires and roofs still enliven the skylines of northern European cities. Improved techniques of pre-patination can now bestow an instant, uniform illusion of maturity; Jean Nouvel's new cultural centre in Lucerne (p38) is crowned by a vast, overhanging roof clad in sheets of prepatinated copper. Sheltering a new urban square in its oversailing embrace, the emerald green structure forms a powerful horizontal datum in the lakeside landscape
Metals have useful properties such as tensile strength, ductility, hardness, electrical conductivity, and high melting points. They are widely used for electrical and structural applications. Understanding the physical and chemical properties of metals allows for improved technological advances. Since metals are so widely used in today's modern world, corrosion is all around us and affects our lives in many ways. Corrosion has many serious consequences to our society such as, economic, health, safety, technological, and cultural.
Cast iron played a pre-eminent role in the industrial development of our country during the 19th century.. As an architectural metal, it made possible bold new advances in architectural designs and building technology, while providing a richness in ornamentation. cast iron in the form of slender, nonflammable pillars, was introduced in the 1790s in English cotton mills, where fires were endemic
In 1849 Bogardus created something uniquely American when he erected the first structure with self-supporting, multi-storied exterior walls of iron. Known as the Edgar Laing Stores, this corner row of small four-story warehouses that looked like one building was constructed in lower Manhattan in only two months. Its rear, side, and interior bearing walls were of brick; the floor framing consisted of timber joists and girders. One of the cast-iron walls was load-bearing, supporting the wood floor joists. The innovation was its two street facades of self-supporting cast iron, consisting of multiples of only a few pieces--Doric-style engaged columns, panels, sills, and plates, along with some applied ornaments. Each component of the facades had been cast individually in a sand mold in a foundry, machined smooth, tested for fit, and finally trundled on horse-drawn drays to the building site. There they were hoisted into position, then bolted together and fastened to the conventional structure of timber and brick with iron spikes and straps.
The second iron-front building erected was a quantum leap beyond the Laing Stores in size and complexity. Begun in April 1850 by Bogardus, with architect Robert Hatfield, the five-story Sun newspaper building in Baltimore was both cast-iron-fronted and cast-iron-framed. In Philadelphia, several iron-fronts were begun in 1850: The Inquirer Building, the Brock Stores, and the Penn Mutuai Building (all three have been demolished). The St. Charles Hotel of 1851 at 60 N. Third Street is the oldest iron-front in America. Framing with cast-iron columns and wrought-iron beams and trusses was visible on a vast scale in the New York Crystal Palace of 1853.
Wrought iron can be distinguished from cast iron in several ways.