User:Milton Beychok/Sandbox: Difference between revisions
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== Scales == | == Scales == | ||
== History == | |||
Knowledge of relative density or specific gravity has been with us since the days of [[Archimedes]] in 250 BC, with the observation that light objects can float while heavier ones will sink in water.<ref>{{cite book|author=T. L. Heath|title=The Works of Archimedes|edition=|publisher=Cambridge University Press|year=1897|pages=page 253|id=}} Full text available at [http://www.archive.org/stream/worksofarchimede00arch#page/n5/mode/2up www.archive.org]</ref> Availa [[Hypatia]] (born ca. 350 and died 415 AD), a [[Greece|Greek]] scholar from [[Alexandria]] in [[Egypt]], is reputed to have invented the hydrometer.<ref>[http://www.inventions.org/culture/female/hypatia.html Mothers of Invention] Ethlie Ann Vare and Greg Ptacek, 1988, pp. 24-26.</ref> | |||
== References == | |||
{{reflist}} | |||
Revision as of 17:54, 2 February 2010
A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids; that is, the ratio of the density of the liquid to the density of water with both at the same temperature. It is usually made of glass and consists of a small diameter cylindrical stem and a larger diameter section weighted with mercury or lead shot (sealed with wax) to make it float upright. The larger diameter section is necessary to provide the displacement volume needed for the proper buoyancy of the hydrometer
The stem contains a rolled paper marked with the scale being used. There are a great many different hydrometer scales commonly used to measure liquid densities in: petroleum crude oil marketing and refining; making wine, brewing beer and making whiskey; producing sulfuric acid and other industrial chemicals; and refining sugar.
Scales
History
Knowledge of relative density or specific gravity has been with us since the days of Archimedes in 250 BC, with the observation that light objects can float while heavier ones will sink in water.[1] Availa Hypatia (born ca. 350 and died 415 AD), a Greek scholar from Alexandria in Egypt, is reputed to have invented the hydrometer.[2]
References
- ↑ T. L. Heath (1897). The Works of Archimedes. Cambridge University Press, page 253. Full text available at www.archive.org
- ↑ Mothers of Invention Ethlie Ann Vare and Greg Ptacek, 1988, pp. 24-26.