ENAMEL a soda-glass, or silicate of sodium, rendered opaque in some specimens by the presence of stannic oxide, or coloured blue in others by means of silicate of copper associated with the sodic silicate, or exhibiting in other specimens a fine yellow colour, due to the presence of antimony and lead, probably in the form of " Naples yellow." Glazes, of a similar character to some of these, were also manu factured by the Egyptians as early as the sixth dynasty. Sepulchral figures, and a variety of other objects familiar to students of Egyptian art, were produced in a substance which has been miscalled " porcelain," and which is, in fact, a frit coated with variously-coloured glazes, of which the most common is of a fine celestial blue colour. This colour is due to the presence of a double silicate of copper and sodium. Beautiful as these glazes unquestionably are, they are not true enamels, since they are not applied to metallic surfaces. It is true that the ancient Egyptians were able to produce an effect not unlike that of enamel ling by inlaying bronze and gold with coloured pastes. But Dr Birch says of the Egyptians that " their real enamelling does not appear to be older than the time of the Ptolemaic and Roman dominion in Egypt." There can be little doubt that the Greeks and Etruscans were acquainted with the art of enamelling. They seem, however, to have practised it to only a very limited extent, and it may be fairly doubted whether they had attained to such a mastery of its details as some writers have assumed. Thus M. Lenormant, writing in 1863, says " Les collections de 1 Europe possedent mainteiiaiit des pieces incontestables qui demontreut pour les ^Igyptiens, les Pheniciens, les Grecs, et les Etrusques, la connaissance des secrets les plus difficiles de 1 emaillerie, ainsi que la pratique de toutes ]es formes et de toutes les applications doiit ce precede pent etre susceptible." Whatever knowledge of enamelling the Greeks may at onetime have possessed, theyappear to have lost itbeforethe 3d century of our era. This is inferred from a famous passage in Philostratus, which was probably written about 240 A.D. Philostratus was a Greek sophist who went from Athens to the court of Julia, the wife of Septimius Severus. The passage is found in the Icones (lib. i. cap. 28), and since attention was first called to it by Buonarroti, it has been quoted by all writers on enamelling; it is, in fact, the earliest distinct reference to the art. " It is said that the barbarians who inhabit the ocean pour these colours," alluding to the coloured decorations of some horse-trap pings, " on to heated bronze, and that they adhere, become as hard as stone, and preserve the designs." l On this passage the learned commentator Olearius remarks, "Celtas intelligit per barbaros in Oceano." It is a vexed question, however, whether the reference applies to the Celts of Britain or to those of Gaul. French writers naturally apply the allusion to the maritime Gauls ; but Mr Franks and some other writers have pointed out that the expression used by Philostratus, lv fl/ceai oj, would refer more appropriately to an insular people, like the Britons. Large numbers of enamelled objects have indeed been found in various parts of England, Scotland, and Ireland. Among these ornamental objects are shields, fibula;, rings, and even bits and other horse-furniture, such as are probably referred to in the passage from the Icones. The ornamenta tion is mostly in that style which has been designated by Mr Franks as late Celtic. Excellent examples are furnished by tha enamels which were found in the Victoria Cave near Settle in Yorkshire, and have been described by Professor Boyd Dawkins ; these are referred to about the 5th century. (See article CAVE, vol. v. p. 270.) It is not improbable that the art of enamelling, after it ceased to bs cultivated in Britain, may have lingered in Ireland, Toi/ra (f)affi Ta ^aSjuara roiy tv Htfeafy /3a/3dpous ft?v TO> which is known to have been a great centre of arts aud sciences during the 6th and 7th centuries. Although such specimens as those just referred to seem to show that enamelling was practised at a very early period in Western Europe, it is nevertheless in the Eastern empire that we find the earliest historic evidence of the art having flourished as an important industry. Byzantium was indeed for centuries the great seat of this industry, which probably dated from at least the time of Justinian. The word smaltum is found for the first time in a life of Leo IV. written in the 9th century. Theophilus, the artist-monk, has left a minute description of the manner in which the Byzantine euamellers of the 10th century carried on their work. Most of the Byzantine enamels were executed on plates of gold, and large numbers have no doubt been destroyed on account of the intrinsic value of the metal. Such specimens as are extant furnish valuable examples of what is known as the cloisonne process. In cloisonnd work, the design is presented in coloured enamels which are separated one from another by means of ribs of metal bent so as to follow the outline of the sub ject. A plate of gold generally formed the basement of the work, and upon this plate the design was traced in slender fillets of gold. These threads were easily bent to the required form, and were fixed upright upon the plaque, so as to form a number of cells for reception of the enamel. The powdered glass, moistened into a paste was carefully introduced into these compartments, and the prepared plate was then fired. To retain the fused enamel, the edges of the plates were slightly turned up, thus forming a rim. After careful cooling, the irregular fused surface was ground down, and polished, when the design appeared in coloured enamels separated by gold partitions, or doisons. In many cases the metal base forms part of the field, and the s ubject is then enamelled in a hollow which has been been beaten out, while the gold forms a brilliant background. Cloisonne enamelling has been employed by the Chinese and Japanese, who, instead of restricting it to flat surfaces of the precious metals, have applied it to copper vases and other large hollow vessels. They also ingeniously attach the metal fillets to the surface of pottery, and thus produce cups, vases, and other objects in porcelain ornamented with cloisonn6 work. Many Chinese aud Japanese enamels are, however, executed by other processes, such as the champ-leve and surface methods, to be afterwards described. The most famous example of Byzantine cloisonnd work is the Pala d Ora at St Mark s, Venice. This magnificent altar- piece contains a number of enamelled panels and medal lions, executed for the most part on gold, though some are on silver. It is believed that the Pala was brought from Constantinople to Venice about the year 1105, and that some of the enamels may be referred to this date ; but probably they are not all of the same period. Among other interesting examples of ancient cloisonne enamel ling, reference may be made to the well-known Alfred Jewel, which was found at Atheluey in Somersetshire in 1693, and is preserved in the Ashmolean Museum at Oxford. The face of the jewel is of rock-crystal, beneath which is a figure-subject in semi-transparent enamels of blue, white, green, and brown. Around the edge is the legend, AELFRED MEG HEHT GEVVRCAN (Alfred ordered me to be made). Possibly this jewel, or at least the enamelled part, was brought from the East, and is not an example of Saxon enamelling. Cloisonne work is also seen in the cross which was obtained from the tomb of Queen Dagmar who died in 1213, in a valuable pectoral cross belonging to Mr A. J. Beresford Hope, and in a small portrait of St Paul on gold, in the Museum of Practical
Geology, London.