tula-work

Century Dictionary and Cyclopedia

1. n. Niello; niellowork; a kind of decorative work somewhat similar to enameling, done chiefly on silver. Niello-work has been long known, and is described by Pliny, by whom its invention is attributed to the Egyptians. It differs from enamel in that this latter is a vitreous compound, while niello is a combination of sulphur with silver, copper, and lead, the relative proportion of the ingredients, as given by different authors, varying greatly. The composition of niello, according to Pliny, is three parts of silver with one of copper, and no lead. All the more modern recipes demand less silver and some lead, the quantity of the precious metal diminishing from century to century. Benvenuto Cellini gives one sixth silver, one third copper, and one half lead as the composition of niello. The above has reference to the metallic ingredients of this article; in its manufacture sulphur is generally added in excess, that which is not taken up by the metals being volatilized in the process, which is performed in a crucible, a little sal ammoniac being used as a flux. Niello-work has been done in Russia for many years, and especially at Tula, which is the best-known locality for this branch of decorative art, although it is said that more artistic specimens are turned out at other places in that country. Niello is called in Russia “black silver.” See niello.