- Goldbeater's skin
Goldbeater's skin — the outer membrane of
calf 'sintestine — is aparchment traditionally used in the process of reducing gold into mere 1μm -thick leaves.Up to 120 sheets of gold laminated with goldbeater's skin can be beaten at the same time, since the skin is thin, elastic and does not tear under heavy "goldbeating".It is used as the sensitive element in
hygrometer s since due to its hygroscopic property, variations in atmospheric humidity cause skin contraction or expansion.Alexander Graham Bell used a drum of goldbeater's skin with an armature of magnetised iron attached to its middle as a sound receiver ("seeInvention of the telephone ") and theNorth German Confederation printed 10- and 30-groschen postage stamp s on goldbeater's skin, to prevent reuse of these high-value stamps.Joseph Thomas Clover invented an apparatus for the inhalation ofchloroform in 1862. This consisted of a large reservoir bag lined with goldbeater's skin to make it airtight, into which a known volume of liquid chloroform was injected [Sykes WS (1960). "Essays on the First Hundred Years of Anaesthesia", Vol. 2, Churchill Livingstone, Edinburgh. ISBN 0 443 02866 4, p. 8.] .Due to its transparency, strength and fairly uniform thickness goldbeater's skin is also used in conservation of manuscripts written on
vellum to repair holes and vellum tears. To manufacture goldbeater's skin the gut ofoxen (or othercattle ) is soaked in a dilute solution ofpotassium hydroxide , washed, stretched, beaten flat and thin, and treated chemically to preventputrefaction . A pack of 1,000 pieces of goldbeater's skin requires the gut of about 400 oxen, and is only 1inch thick.References
* [http://aic.stanford.edu/sg/bpg/annual/v02/bp02-15.html Notes on the Manufacture of Goldbeater's Skin by Jack C. Thompson]
* [http://palimpsest.stanford.edu/don/dt/dt1574.html Bookbinding and the Conservation of Books. Goldbeater's skin.]
* [http://www.karger.com/gazette/67/Fuchs/art_5.htm The History and Biology of Parchment by Robert Fuchs]External links
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