Speculum metal


Speculum metal

Speculum metal is a very hard white alloy of four parts copper to one part tin, or according to [http://www.astronomybuff.com/leviathan-of-parsonstown/ other sources] , three parts copper to one part tin; some compositions contained 1–2% of arsenic. Composition with 45% tin has more resistance to tarnishing.

It was used by some early telescope makers. For instance, Lord Rosse in 1845 used the alloy for the 72-inch mirror of his "Leviathan of Parsonstown" telescope. The metal has the unfortunate property of tarnishing rapidly, requiring constant re-polishing that can easily disfigure a telescope mirror.

Use of speculum metals for mirrors declined after 1859, when Leon Foucault published his results on silvered glass parabolical mirrors.

ee also

* Bronze

External links

* [http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet]


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Look at other dictionaries:

  • Speculum metal — Speculum Spec u*lum, n.; pl. L. {Specula}, E. {Speculum}. [L., fr. specere to look, behold. See {Spy}.] 1. A mirror, or looking glass; especially, a metal mirror, as in Greek and Roman arch[ae]ology. [1913 Webster] 2. A reflector of polished… …   The Collaborative International Dictionary of English

  • speculum metal — n. an alloy of copper and tin that will take a mirrorlike polish, used for making mirrors …   English World dictionary

  • speculum metal — veidrodinis metalas statusas T sritis fizika atitikmenys: angl. speculum metal vok. Spiegelmetall, n rus. зеркальный металл, m pranc. métal à miroir, m …   Fizikos terminų žodynas

  • speculum metal — any of several bronze alloys with a high tin content, often containing other materials, as silver, brass, lead, zinc, or arsenic, used for making mirrors and reflectors. Also called speculum, speculum alloy. [1790 1800] * * * …   Universalium

  • Speculum metal — Spiegelmetall ist eine sehr harte, gut polierbare, weißliche Bronzelegierung aus Kupfer, Zinn und Zusätzen anderer Metalle, die die Härte und Polierbarkeit verbessern. Legierungen Einige für Spiegel verwendete Legierungen sind: einfache… …   Deutsch Wikipedia

  • speculum metal — noun an alloy of copper and tin used to make mirrors, especially formerly for telescopes …   English new terms dictionary

  • speculum metal — /ˈspɛkjələm mɛtl/ (say spekyuhluhm metl) noun any of several copper and tin alloys used for mirrors and reflectors …   Australian English dictionary

  • speculum metal — noun : an alloy capable of taking a brilliant polish, used for making reflectors, and being commonly a hard brittle alloy of copper and tin in various ratios (as tin 33 to copper 67) with often a little arsenic, antimony, or zinc added to improve …   Useful english dictionary

  • Speculum — Spec u*lum, n.; pl. L. {Specula}, E. {Speculum}. [L., fr. specere to look, behold. See {Spy}.] 1. A mirror, or looking glass; especially, a metal mirror, as in Greek and Roman arch[ae]ology. [1913 Webster] 2. A reflector of polished metal,… …   The Collaborative International Dictionary of English

  • Speculum — Spec u*lum, n.; pl. L. {Specula}, E. {Speculum}. [L., fr. specere to look, behold. See {Spy}.] 1. A mirror, or looking glass; especially, a metal mirror, as in Greek and Roman arch[ae]ology. [1913 Webster] 2. A reflector of polished metal,… …   The Collaborative International Dictionary of English


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