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Vintage Revere Ware, manufactured before 1968 and carrying the prized "Process Patent" maker's mark on the thick copper bottom, is finding its way back into modern kitchens. (Photo courtesy of Blane van Pletzen-Rands) Revere Ware was a line of consumer and commercial kitchen wares introduced in 1939 by the Revere Brass & Copper Corp.
There is evidence that gold and meteoric iron (but not iron smelting) were the only metals used by humans before copper. [3] The history of copper metallurgy is thought to have followed the following sequence: 1) cold working of native copper , 2) annealing , 3) smelting , and 4) the lost wax method .
A mirror reflecting the image of a vase A first-surface mirror coated with aluminium and enhanced with dielectric coatings. The angle of the incident light (represented by both the light in the mirror and the shadow behind it) exactly matches the angle of reflection (the reflected light shining on the table). 4.5-metre (15 ft)-tall acoustic mirror near Kilnsea Grange, East Yorkshire, UK, from ...
In the early 10th century, the Persian scientist al-Razi described ways of silvering and gilding in a book on alchemy, [citation needed] but this was not done for the purpose of making mirrors. Tin-coated mirrors were first made in Europe in the 15th century. The thin tinfoil used to silver mirrors was known as "tain". [5]
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The composition of speculum metal was further refined and went on to be used in the 1700s and 1800s in many designs of reflecting telescopes. The ideal composition was around 68.21% copper to 31.7% tin; more copper made the metal more yellow, more tin made the metal more blue in color. [10]
For example, knowing that standard 18-karat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by mass), the volume of pure gold in this alloy will be 60% since gold is much denser than the other metals used: 19.32 g/cm 3 for gold, 10.49 g/cm 3 for silver and 8.96 g/cm 3 for copper.
The troy ounce is heavier than the avoirdupois ounce, a commonly used unit for measuring weight in the United States customary system. [ 5 ] The standard gold bar held and traded internationally by central banks and bullion dealers is the Good Delivery bar with a 400 ozt (12.4 kg; 27.4 lb) nominal weight.
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