NIEL'LO (It., blackish). A black substance capable of being ground fine and also of being melted by a moderate heat. The ingredients are essentially silver and sulphur, but other metals are melted with the silver before the sulphur is added. It is used as enamel is used, to fill up incised lines and patterns, the metal background being nearly always silver. Thus the top and sides of a silver box 111 ay be engraved with in scrolls, conventional flow ers, and the like; the separate parts are heated, the powdered Mello is spread over the whole surface, and as it melts, fills every incision, even the finest lines and points. The metal is then cleaned and polished, so that the smooth surface shows a black path•rn on a plain silver ground. In some modern work the black pattern is slight ly in this suggests the application of the ground and nearly fused Mello by hand to the actual lines of the pattern.
The art of working in niello dates from an tiquity. It was in common use under the Byzan
tine Empire, and this tradition has been inherited by the modern Russians, together with so many other forms of decorative art. It was also prac ticed in Western Europe throughout the Niddle Ages, though it was less popular than enamel, A great deal of altar plate and similar decorative objects belonging to the Christian ritual were adorned by niello. The metal-workers of India have always employed the art with high success. Consult: Ottley, History of Engrari»g (London, 1816) : Duchesne. Essai sur les niclles grarures des orftrres florentins du Xl'eqne siCele (Paris, 1826) ; Waterton, "On Niello," in Areturological Journal, vol. six. (London, 1862) ; Passavant, Le pcintre-grarcur (Leipzig, 1S60-64) : Labarte, Arts of the Middle Ayes (2d ed., Paris, 1872-751 ; Davenport, "Niello Work," in Journal of the So ciety of Arts, vol. xlviii.(London, 1901).