Goldbeater's skin — the outer membrane of calf

Calf

Calves are the young of domestic cattle. Calves are reared to become adult cattle, or are slaughtered for their meat, called veal.-Terminology:...

's intestine

Intestine

In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...

 — is a parchment

Parchment

Parchment is a thin material made from calfskin, sheepskin or goatskin, often split. Its most common use was as a material for writing on, for documents, notes, or the pages of a book, codex or manuscript. It is distinct from leather in that parchment is limed but not tanned; therefore, it is very...

  traditionally used in the process of making gold leaf

Gold leaf

right|thumb|250px|[[Burnishing]] gold leaf with an [[agate]] stone tool, during the water gilding processGold leaf is gold that has been hammered into extremely thin sheets and is often used for gilding. Gold leaf is available in a wide variety of karats and shades...

 by beating, 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

Goldbeating

Goldbeating is the process of hammering gold into an extremely thin unbroken sheet for use in gilding.- History :5,000 years ago, Egyptian artisans recognized the extraordinary durability and malleability of gold and became the first goldbeaters and gilders. They pounded gold using a round stone to...

.

To manufacture goldbeater's skin, the gut of oxen (or other cattle

Cattle

Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...

) is soaked in a dilute solution of potassium hydroxide

Potassium hydroxide

Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...

, washed, stretched, beaten flat and thin, and treated chemically to prevent putrefaction

Putrefaction

Putrefaction is one of seven stages in the decomposition of the body of a dead animal. It can be viewed, in broad terms, as the decomposition of proteins, in a process that results in the eventual breakdown of cohesion between tissues and the liquefaction of most organs.-Description:In terms of...

. A pack of 1,000 pieces of goldbeater's skin requires the gut of about 400 oxen, and is only 1 inch thick.

Uses

Goldbeater's skin is used as the sensitive element in hygrometer

Hygrometer

A hygrometer is an instrument used for measuring the moisture content in the environmental air, or humidity. Most measurement devices usually rely on measurements of some other quantity such as temperature, pressure, mass or a mechanical or electrical change in a substance as moisture is absorbed...

s, since, due to its hygroscopic

Hygroscopy

Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment. This is achieved through either absorption or adsorption with the absorbing or adsorbing material becoming physically 'changed,' somewhat, by an increase in volume, stickiness, or other...

 property, variations in atmospheric humidity cause skin contraction or expansion. Alexander Graham Bell

Alexander Graham Bell

Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone....

 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

Invention of the telephone

The invention of the telephone is the culmination of work done by many individuals, the history of which involves a collection of claims and counterclaims. The development of the modern telephone involved an array of lawsuits founded upon the patent claims of several individuals...

) and the North German Confederation

North German Confederation

The North German Confederation 1866–71, was a federation of 22 independent states of northern Germany. It was formed by a constitution accepted by the member states in 1867 and controlled military and foreign policy. It included the new Reichstag, a parliament elected by universal manhood...

 printed 10- and 30-groschen

Groschen

Groschen was the name for a coin used in various German-speaking states as well as some non-German-speaking countries of Central Europe , the Danubian principalities...

 postage stamp

Postage stamp

A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...

s on goldbeater's skin, to prevent reuse of these high-value stamps. Joseph Thomas Clover invented an apparatus for the inhalation of chloroform

Chloroform

Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...

 in 1862 which 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 to repair holes and tears in manuscripts written on vellum

Vellum

Vellum is mammal skin prepared for writing or printing on, to produce single pages, scrolls, codices or books. It is generally smooth and durable, although there are great variations depending on preparation, the quality of the skin and the type of animal used...

.

In the early 1900s large quantities of goldbeater's skin were used to make the gas bags of rigid airship

Rigid airship

A rigid airship is a type of airship in which the envelope retained its shape by the use of an internal structural framework rather than by being forced into shape by the pressure of the lifting gas within the envelope as used in blimps and semi-rigid airships.Rigid airships were produced and...

s, exhausting the available supply: about 200,000 sheets were used for a typical World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 Zeppelin

Zeppelin

A Zeppelin is a type of rigid airship pioneered by the German Count Ferdinand von Zeppelin in the early 20th century. It was based on designs he had outlined in 1874 and detailed in 1893. His plans were reviewed by committee in 1894 and patented in the United States on 14 March 1899...

, while the USS Shenandoah

USS Shenandoah (ZR-1)

USS Shenandoah was the first of four United States Navy rigid airships. It was built in 1922-1923 at Lakehurst Naval Air Station, and first flew in September 1923. It developed the Navy's experience with rigid airships, even making the first crossing of North America by airship...

 needed 750,000 sheets. The sheets were joined together and folded into impermeable layers.

Goldbeater's skin (sometimes also called "fish skin" in this context) is sometimes also used to seal oboe

Oboe

The oboe is a double reed musical instrument of the woodwind family. In English, prior to 1770, the instrument was called "hautbois" , "hoboy", or "French hoboy". The spelling "oboe" was adopted into English ca...

 reed

Double reed

A double reed is a type of reed used to produce sound in various wind instruments. The term double reed comes from the fact that there are two pieces of cane vibrating against each other. A single reed consists of one piece of cane which vibrates against a mouthpiece made of metal, hardened...

s, to prevent them from leaking air.Goldbeaters' skin for Oboe - large - Oboe Reed-making - Britannia Reeds

The gold beater skin test is used to assess the tannin

Tannin

A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...

g properties of a compound (when gold beater skin or ox skin is dipped in hydrochloric acid

Hydrochloric acid

Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

 and treated with one percent ferrous sulfate

Iron(II) sulfate

Iron sulfate or ferrous sulfate is the chemical compound with the formula FeSO4. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material...

solution, after washing with water it gives a blue-black colour).