White copper
White copper or White tombac , also cuprum album is a bright copper - arsenic - alloy which was earlier (usually silver) as a replacement of silver used. It contained 63% copper and 37% arsenic. Since the middle of the 19th century , white copper has been largely replaced by the copper-nickel-zinc alloy German silver due to its toxicity . After the white copper was replaced by German silver, the name "white copper" was also partially transferred to the successor alloy.
The alloy was produced by melting together equal parts of elemental copper and arsenic, also equal parts of copper shavings and arsenic (III) oxide ( arsenic ) and carbon (mostly as soot ) as a reducing agent . Since the alloy was then mostly not homogeneous in color, the heating was repeated several times until the reddish color had disappeared and the mixture took on a uniform, silvery color. The white copper obtained is a brittle, fragile substance that only resembles silver in color and turns yellow to black in the air. Equipment was almost always covered with silver leaf to improve durability.
White copper was used for candlesticks, metal utensils and vessels; The use of white copper devices for the preparation of food and drinks was discouraged from an early stage.
In the English-speaking world, "white copper" refers to the alloy "nickel silver".
Individual evidence
- ^ Johann Joseph von Prechtl , Karl Karmarsch : Technological Encyclopedia or alphabetical manual of technology, technical chemistry and mechanical engineering. Volume 9: Copper - Metal Foundry. Cotta, Stuttgart 1838, p. 36.
- ↑ a b Friedrich Wilhelm Barentin: Textbook of technology for secondary and commercial schools. 3. Edition. Heyer, Giessen 1848, p. 15.
- ^ Johann Tenner: Handbook of metal alloys. 2nd Edition. Basse, Quedlinburg 1860, p. 37.
- ↑ a b Martin Heinrich Klaproth , Friedrich Wolff: Chemical dictionary: Se - Z. Volume 5. Voss, 1810, p. 672.