“GOLDBEATER’S SKIN”

Greymouth Evening Star, 28 November 1929, Page 3

“GOLDBEATER’S SKIN”

DIRIGIBLES’ OVERCOATS.

Thousands of cattle have contribute ed from time to time to the making of > dirigible airships. The membrane! known for centuries as goldbeater’s skin comes from an obsolete stomach or kind of appendix in certain animals (says an overseas paper). For the past 20 years Governments of Europe and Departments . in the; United States have been seeking a; suitable substitute for this precious; membrane used in making gas cellsfor lighter-than-air flying machines. The skins as taken from the cattle are small and cost between lOd and 1/3 apiece. Ultimate processes bring the 1 cost, measured in feet and inches, to' about £2 <per square yard. The size of a modern airship requires 30,000' square yards of the membrane for its> gas cells. . Recognition of the value of the dirigible airships in war and commerce has spurred the world powers to seek a less expensive material with'which to line the great gas envelopes on which dirigibles depend for buoyancy. Goldbeater’s skin weighs less than three-quarters of an ounce to- the ; square yard, and . allows a minimum escape of gas. In finished form, applied to cotton cloth and covered with varnish, it weighs about four ounces to,- the square yard, which is considerably less than the best rubberised substitute, yet produced. Goldbeater’s skin for twenty centuries or more has been used as interleaving in hammering gold into leaf form. Placed between sheets of the skin it is possible to reduce the metal to 1-200-000 of an inch in thickness. Without interleaving, the gold would cling to the hammer, when it was an eighth of an inch thick and thereafter become impracticable for working without, some artificial aid such aS' the skin described.