isinglasses

Noun

isinglass (usually uncountable, plural isinglasses)

1. (usually) A form of gelatin obtained from the air bladder of the sturgeon and certain other fish, used as an adhesive and as a clarifying agent for wine and beer.
   • Isinglass flummery.—Put six ounces of isinglass into a quart of new milk, sweeten it, set it over the fire, and keep it stirring one way all the time, till it is jellied; pour it into basins, and when cold turn it out; you may put in orange flower water if you like.1830, Richard Dolby, The Cook's Dictionary, and House-keeper's Directory: A New Family Manual of Cookery and Confectionery, on a Plan of Ready Reference Never Hitherto Attempted, London: Henry...
2. (usually) A thin, transparent sheet of mica (probably from its similarity to true isinglass and/or resulting from confusion with the term Muscovy glass for glazing made from mica, but also used for isinglass, which was chiefly produced in the Caspian Sea region of Russia, or Muscovy).
   • TALC. / GENUS I. / ISINGLASS. / VITRUM. / Compoſed of broad, flat, cloſe, poliſhed Plates.1771, J[ohn] Hill, Fossils Arranged According to their Obvious Characters; with their History and Description; under the Articles of Form, Hardness, Weight, Surface, Colour, and Qualities; the Place...