Goldbeater's skin
— the outer membrane of
calf's
intestine — is a
parchment 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.
To manufacture
goldbeater's skin, the gut of
oxen
(or other
cattle) is soaked in a dilute solution of
potassium hydroxide, washed, stretched, beaten flat and
thin, and treated chemically to prevent
putrefaction. A pack of 1,000 pieces of goldbeater's skin
requires the gut of about 400 oxen, and is only 1 inch thick.
[edit]
Uses
It is used as
the sensitive element in
hygrometers, 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 (see
Invention of the telephone) and the
North German Confederation printed 10- and 30-groschen
postage stamps on goldbeater's skin, to prevent reuse of
these high-value stamps.
Joseph Thomas Clover invented an apparatus for the
inhalation of
chloroform 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.[1]
Due to its transparency, strength, and fairly uniform thickness,
goldbeater's skin is also used to repair holes and tears in
manuscripts written on
vellum.
In the early
1900s large quantities of goldbeater's skin were used to
make the gas bags of
rigid airships, exhausting the available supply: about
200,000 sheets for a typical World War 1
Zeppelin, while the
USS Shenandoah needed 750,000 sheets.[2]
The sheets were joined together and folded into impermeable
layers.[2]
Goldbeater's
skin (sometimes also called "fish skin" in this context) is
sometimes also used to seal
oboe
reeds, to prevent them from leaking air.[3]
The gold beater
skin test is used to assess the
tanning properties of a compound (when gold beater skin or
ox skin is dipped in
HCl & treated with 1%
FeSO4 solution, after washing with water it gives
a blue / black colour).
[edit]
References
-
^
Sykes WS (1960). Essays on the First Hundred
Years of Anaesthesia, Vol. 2, Churchill
Livingstone, Edinburgh.
ISBN 0 443 02866 4, p. 8.
-
^
a
b
Steadman, Mark
(2006-05-01).
"The Goldbeater, the Cow and the Airship".
Post & Tele Museum, Denmark.
http://www.ptt-museum.dk/en/online_magazine/previous_articles/broadcasting/?id=74.
Retrieved 2009-09-12.
-
^
Goldbeaters' skin for Oboe - large - Oboe
Reed-making - Britannia Reeds
-
Notes on the Manufacture of Goldbeater's Skin by
Jack C. Thompson
-
Bookbinding and the Conservation of Books.
Goldbeater's skin.
-
The History and Biology of Parchment by Robert
Fuchs
[edit]
External
links
-
Balloon fabrics made of Goldbeater's skins by
Chollet, L. Technical Section of Aeronautics.
December 1922PDF (472 KB)
Retrieved from "http://en.wikipedia.org/wiki/Goldbeater%27s_skin"
