COLORATION OF GLASS BY GOLD, SILVER, AND COPPER*

Abstract

A bstract A discussion of hypotheses concerning the development of gold ruby, silver yellow, and copper ruby colors in silicate glass is presented. Experiments are described which were designed to determine whether gold dissolves in molten silicate glasses in an oxidized (ionic) state or as uncombined metal. Results are believed to prove that gold dissolves as ions rather than in the metallic state. Similar conclusions apply to silver and copper. The metal coloration results from reduction of the metal ions to insoluble metal at low temperatures, the reducing agent being Sn +2 , or other polyvalent ions, as postulated by Badger, Weyl, and Rudow and by Dietzel.