NIELLO (Italian form of Latin nigellum, diminutive of niger, " black " ; late Greek, _____), a method of producing delicate and minute decoration on a polished metal surface by incised lines filled in with a black metallic amalgam. In some cases it is very difficult to distinguish niello from black enamel ; but the black substance differs from true enamel in being metallic, not vitreous. Our knowledge of the process and materials employed in niello-work is derived mainly from four writers, - Eraclius the Roman (a writer probably of the 11th century), Theophilus the monk, who wrote in the 12th or 13th century,' and, in the 16th century, Ben. Cellini 2 and Giorgio Vasari.3 These, with the exception of Eraclius, whose account is slightly different, agree closely in their description of the process. The design was cut with a sharp graving tool on the smooth surface of the metal, which was usually silver, but occasionally gold or even bronze. An alloy was formed of two parts silver, one-third copper, and one-sixth lead ; to this mixture, while fluid in the crucible, powdered sulphur in excess was added; and the brittle amalgam, when cold, was finely pounded, and sealed up in large quills for future use. A solution of borax to act as a flux was brushed over the metal plate and thoroughly worked into its incised lines. The powdered amalgam was then shaken out of the quills on to the plate, so as to completely cover all the engraved pattern. The plate was, now carefully heated over a charcoal fire, fresh amalgam being added, as the powder fused, upon any defective places. When the powder had become thoroughly liquid, so as to fill all the lines, the plate was allowed to cool, and the whole surface was scraped, so as to remove the superfluous niello, leaving only what had sunk into and filled up the engraved pattern. Last of all the nielloed plate was very highly polished, till it presented the appearance of a smooth metal surface enriched with a delicate design in fine grey-black lines. This process was chiefly used for silver work, on account of the vivid contrast between the whiteness of the silver and the darkness of the niello. As the slightest scratch upon the metal received the niello, and became a distinct black line, ornament of the most minute and refined description could easily be produced.
The earliest specimens of niello now existing belong to the Roman period. Two fine examples are in the British Museum. One is a bronze statuette of a Roman general, nearly 2 feet high, found at Barking Hall in Suffolk. The dress and armour have patterns partly inlaid in silver and partly in niello. The dark tint of the bronze rather prevents the niello from showing out distinctly. This statuette is apparently a work of the 1st century.4 The other example is not earlier than the 4th century. It is a silver casket or lady's toilet box, in which were found an ampulla and other small objects, enriched with niellowork.5 From Roman times till the end of the 16th century the art of working in niello seems to have been constantly practised in some part at least of Europe, while in Russia and India it has survived down to the present day. From the 6th to the 12th century an enormous number of most massive and splendid works in the precious metals were produced at Byzantium or under Byzantine influence, many of which were largely decorated with niello ; the silver dome of the baldacchino over the high altar of S. Sophia was probably one of the most important of these. Niello is frequently mentioned in the inventories of the treasures belonging to the great basilicas of Rome and Byzantium. The Pala d'Oro at S. Mark's, Venice, 10th century (see METAL-WORK), owes much of its refined beauty to niello patterns in the borders. This art was also practised by Bernard, artist-bishop of Hildesheim (ob. 1023) ; a fine silver paten, decorated with figures in niello, attributed to his hand, still exists among the many rich treasures in the church of Hanover Palace. Other nielli, probably the work of the same bishop, are preserved in the cathedral of Hildesheim. In France too, judging both from existing specimens of ecclesiastical plate and many records preserved in church inventories, this mode of decoration must have been frequently applied all through the Middle Ages : especially fine examples once existed at Notre Dame, Paris, and at Cluny, where the columns of the sanctuary were covered with plates of silver in the 11th century, each plate being richly ornamented with designs in niello. Among the early Teutonic and Celtic races, especially from the 8th to the 11th centuries, both in Britain and other countries, niello was frequently used to decorate the very beautiful personal ornaments of which so many specimens enrich the museums of Europe. The British Museum possesses a fine fibula of silver decorated with a simple pattern in niello and thin plates of repousse gold. This, though very similar in design to many fibulae from Scandinavia and Britain, was found in a tomb at Kertch (Panticapum).8 Several interesting gold rings of Saxon workmanship have been found at different NIELLO times, on which the owner's name and ornamental patterns are formed in gold with a background of niello. One with the name of Ethelwulf, king of Wessex (836-838), is now in the British Museum (see figure). Another in the South Kensington Museum has the name of Alhstan, who was bishop of Sherborne from 823 to $.67. The metal-workers of Ireland, whose skill was quite unrivalled, practised largely the art of niello from the 10th to the 12th cen- - tury, and possibly even earlier. Fine croziers, shrines, fibul, and other objects of Irish workmanship, most skilfully enriched with elaborate niello-work, exist in considerable numbers. From the 13th to the 16th century but little niello-work appears to have been produced in England. Two specimens have been found, one at Matlask, Norfolk, and the other at Devizes, which from the character of the design appear to be English. They are both of gold, and seem to be the covering plates of small pendent reliquaries, about an inch long, dating about the end of the 15th century. One has a crucifix between St John the Baptist and a bishop ; the other, that found at Devizes, has the two latter figures, but no crucifix.7 It is, however, in Italy that the art of niello-work was brought to greatest perfection. During the whQle medimval period it was much used to decorate church plate, silver altar-frontals, and the like. The magnificent frontals of Pistoia cathedral and the Florence baptistery are notable instances of this.8 During the 15th century, especially at Florence, the art of niello-work was practised by almost all the great artistgoldsmiths of that period. Apart from the beauty of the works they produced, this art had a special importance and interest from its having led the way to the invention of printing from engravings on metal plates. For the description of how this happened see ENGRAVING, VOL viii. p. 439. Vasari's account of this invention, given in his lives of Pollajuolo and Maso Finiguerra (Vite dei Pittori e Scultori), is very interesting, but he is probably wrong in asserting that Maso was the first worker in niello who took proofs or impressions of his plates. The most important work of this sort by Maso Finiguerra, described at length by Vasari, still exists in the Opera del Duomo at Florence. It is a pax with a very rich and delicate niello picture of the coronation of the virgin ; the composition is very full, and the work almost microscopic in minuteness ; it was made in 1452. Impressions from it are preserved in the British Museum, the Louvre, and other collections. Among the many great Italian artists who were also niellists occur the names of Brunelleschi, Ant. Pollajuolo, Baccio Baldiui, Francia, Pellegrino da Cesena, Cellini, Caradosso, and Foppa. Some fine specimens signed by Francia are preserved in the Bargello at Florence. The British Museum, the Louvre, the Berlin Museum, and the royal gallery of Vienna are especially rich both in nielli and in sulphur and paper impressions. The British Museum also possesses the finest existing example of 15th-century German niello. It is a silver beaker, covered with graceful scroll-work, forming medallions, in which are figures of cupids employed in various occupations ;1 it is a very remarkable piece of silver-work, both for design and beauty of execution. The art of niello-work is still practised with considerable skill both in Russia and in various parts of India. The " bidri work," so called from Bedar in Hyderabad, is a variety of niello, in which the pattern shows as silver on a niello ground. The modern revival of the art in Paris has been hitherto very unsuccessful.
Literature. - The Archzological Journal (vol. xix. p. 323) has an excellent monograph on the subject, see also vol. xii. p. 79 and vol. iv. p. 247; Arehteologia, vol. xxxi. p. 404; Merrifield, Ancient Practice of Painting, vol. i., 1849 (gives MSS. of Eraclius and other early writers); Catalogue of Museum of Royal Irish Academy ; Les Nielles a la Cath. d'Aix-la-Chapelle, Paris, 1859; Alvin, Niclles de la Bibliotheque roy. de Belgique, 1857; Duchesne, Nielles des Orfevrcs Florentine, 1826; Passavant, Le Peintregraveur, 1860-64 ; Ottley, History of Engraving (1816) and Collection of Fac-similes of Prints (1826); Cicognara, Storia Bella Seultura (iii. p. 168, Prato, 1823) and Storia della Calcografia, (Prato, 1831); Lanzi, Storia Pittorica, ep. i. sec. iii., 1809; Baldi- nucci Professori del Disegno (1681-1728) and L'Arte di lntagliare in dame (1686); Zani, Origin dell' Incision in Rame, 1802; Labarte, Arts of the Middle Ages, 1855; Texier, Dietionnairc de l'Orftvrerie, p. 1822, Paris, 1857; Bartsch, Le Peintre-graveur, vol. xiii. pp. 1-35; Rumohr, Untersuchung der Grande far die Annahme, &c., Leipsic, 1841; and Lessing, Collectaneen zur Litteratur (vol. xii. art. Niellum "). (J. H. m.)