-71 



KMYMN. 



i:\.\MKl.S AND l:\.\MI-.I. \\OHK. 



87J 



rate or become aoid. Almond* and some other substances are directed 

 to be kept in the state of dry confection* [COSFKCTIONS], and these 

 can immediately be formed into emulaions by triturotion with i-ith.-r 

 paw or dUtilled aromatic waters. Castor oil may readily be made into 

 an emulsion by merely miring it, and stirring it well, in warm milk or 

 coffee. By this means it not only acts more rapidly, but a much 

 smaller dose is required. It can also be formed into a real emulsion 

 by mixing it in any aromatic water, such as dill r cinnamon, to which 

 a few drops of caustic potass (liquor potassse), have been added. But 

 in this latter ease, the large ordinary dose is needful. 



EMYDIN. A neutral azotlsed substance contained in tho yolk of 

 tortoises' eggs, and bearing a considerable resemblance to Icimnv 

 According to the analysis of Fremy, it consists of 



Carbon 49-4 



Hydrogen 7 '4 



Nitrogen 14-6 



Oxygen 1 

 Phosphorus f 



Emydin presents the appearance of white, hard, and transparent 

 grains, very soluble in dilute solution of potash. It dissolves in boiling 

 hydrochloric acid, without producing a violet colour ; in acetic acid it 

 swells up, but does not dissolve. On incineration it leaves about one 

 per cent of a calcareous ash. 



ENAMELS AND ENAMEL-WORK. The subject of this article 

 will best be treated under three sections Enamels, in their character 

 and mode of employment ; enamel -painting, as a branch of the fine- 

 arts ; and enamelled-ware, as a manufactured product. 



1 . Kxamdt. These are verifiable substances, or a peculiar prepara- 

 tion of glass, to which different colours are given, sometimes preset -\ -in;:, 

 sometimes depriving it of its transparency. Artists and jewellers 

 distinguish three kinds of enamels ; those which are used to imitate 

 precious stones, those employed in enamel painting (painting on 

 enamel), and those with which an infinite variety of small works are 

 made. The preparation of enamels is very various. In general, ten 

 parts of lead and three parts of tin ore oxidised by continued heat 

 and exposure to air. To the mixed oxides thus obtained must be 

 added ten parts of powdered quartz or flint and two ports of common 

 salt, and the whole must be properly melted in a crucible ; thus we 

 obtain a white enamel and the basis of coloured enamel, metallic 

 oxides being added in the preparation at the very beginning to give the 

 required colour. The addition of oxide of lead or antimony produces 

 a yellow enamel ; reds are obtained by a mixture of the oxides of gold 

 and iron, that composed of gold being the most beautiful and durable. 

 The oxides of copper, cobalt, and iron, give greens, violets, and blues ; 

 and a great variety of intermediate colours is produced by mixing 

 them in different proportions. The oxides are sometimes mixed before 

 they are united to the vitreous basis. These are the principal ingre- 

 dients in the composition of enamels ; but the proportions in which 

 they are used, the degree and continuance of the heat required for 

 their perfection, are secrets which the manufacturers carefully keep to 

 themselves as far as they are able. 



The art of practically applying these enamels is of great antiquity. 

 It was practised by the Egyptians, from whom it probably passed to 

 the Greeks, and subsequently to the Romans, who are supposed to 

 have introduced the art into Britain. The art continued to be 

 practised by the Byzantines and by the ecclesiastical artists of the 

 middle ages. In this country it was in use among the Britons, the 

 Saxons, and the Normans successively, as is proved by various specimens 

 still existing ; and thence down to our own times. Anciently enamels 

 were principally applied to ornamental purposes; but since the in- 

 vention of clocks and watches their usefulness has increased in an 

 extraordinary degree, there being probably no substance for dial-plates 

 equal to enamel in durability and beauty. The various processes in 

 the practice of enamelling, like the composition of enamels noticed in 

 the last paragraph, hare probably never been completely made known 

 to the public; they require extraordinary care and attention, and 

 artists who may have been so fortunate as to discover any improved 

 mode of operating are commonly too jealous to make it known. 



Enamels being commonly laid on a metal ground, the first business 

 is to prepare the plates, technically called copperi, to receive the 

 enamel. This preparation requires much care and nicety, and the 

 process is extremely curious. The metals used to enamel upon are 

 gold, silver, and copper. Of the other metals some are too fusible to 

 bear the fire, and the others, as platinum, &c., are too ttrong, as it is 

 termed, for the enamel. The best substance to enamel upon is gold, 

 the richness of the colour giving a beautiful tinge through the enamel ; 

 but, except for watch-cases and valuable articles of jewellery, copper 

 u generally used on account of its cheapness. Both the gold and the 

 copper should be of the finest kinds. 



Enamelling is divided chiefly into two branches, dial-plate enamel- 

 ling and transparent enamelling; the former including the manufac- 

 ture of clock and watch plates, with fluxed plates for enamel painting ; 

 the other the enamelling of watch-case*, brooches, and other trinkets. 

 The artistic branch is noticed here ; various applications to the useful 

 art* will be treated in the latter part of thin article. The enamel as 

 it comes from the maker is commonly in small cakes four, five, or six 

 inches in diameter. In preparing it for use it is split, by means of a 



small hammer applied to the edge of the cakes, into thin flakes, which 

 iro put into an agate mortar and finely pulverised ; the powder is tncn 

 washed with water. The moistened mass is laid very smooth on tin- 

 metal ground with a spatula, and when dried is melted, or, at it w 

 called, nr,<l, under a muffle, in a small furnace heated with coke and 

 coal. The back of the coppers is first covered with enamel, and then 

 the face, to which two coats are given, the operation of firing being 

 applied to each. The plates are then carefully polished, for which 

 various substances are used ; and when this is complete, they are put 

 'or the third and last time into the fire before painting. 



2. Enamel Painting. Supposing an enamelled gold or copper plate 

 a have been prepared, we have next to notice the difficult and dflii-au- 

 iroeoas of enamel painting. This art, which should be called painting 

 on enamel, is of modern date. It has indeed been supposed that i !,, 

 encaustic painting of the ancients was the same thing as our enamel 

 painting. But though the ancients possessed the art of colouring glass, 

 vhich might have led to enamel painting, they do not seem to have 

 acquired this latter art, the invention of which, as it is practised in our 

 days, is ascribed to the French. In 1632, Jean Toutin, a goldsmith at 

 Chateaudun, painted on enamel ; and he and his disciple, Gulden, taught 

 others. Jean Petitot, born at Geneva in 1607, an admirable painter in 

 miniature, carried the art of painting on enamel to a degree of perfection 

 never before attained. He resided long in England ; and French writers 

 affirm that he obtained the knowledge of the most beautiful and 

 durable colours for enamel painting from Sir Theodore Mayence, at 

 Condon, an eminent physician and chemist, who generously communi- 

 cated his secrets to him, and recommended him to Charles I. After 

 he king's death Petitot went to Paris, where he was highly favoured 

 >y Louis XIV., and gained a large fortune. Consequent on the revo- 

 cation of the edict of Nantes he withdrew to Geneva. 



Mr. Digby Wyatt, in a paper read before the Society of Arts, has 

 .raced the progress of artistic enamelling, from the time when it was 

 merely a kind of mosaic work, down to recent days, when the resources 

 of the painter are brought to bear upon it. He traces six stages or 

 aiding varieties, succeeding each other in a definite order ; they were 

 marked by attempts either to improve the fixature of the vitreous 

 >aste on its metallic base, or to increase the external adornment. 

 The first, or Ity-.nuiinc style, was practised throughout the Eastern 

 empire from tho time of Justinian down to about the year 1300. The 

 jest known works of this kind were executed by Theophilus, the cele- 

 brated artist-monk of the llth or 12th century. The chief peculiarity 

 of the process was in the formation of cavities or cells of gold filagree, 

 :or the reception of the enamel. The second, or Early Limoget style, 

 was much practised in that city from the llth to the 14th centuries ; 

 t consisted in forming incisions in a thick copper plate by the graver, 

 for the reception of the enamel, in substitution of the Byzantine or 

 filagree method. The third, or Early Italian style, was practised from 

 about the close of the 13th century to that of the 16th. The most 

 celebrated artist in this method was Ugolino Veri, who executed the 

 shrine in the Orvicto Cathedral in 1333 ; but it was afterwards much 

 practised by goldsmiths and enamellers. It appears to have occupied 

 i midway position between the ancient champ lert, or incised enamel, 

 and the painted enamels afterwards produced ; it consisted in engraving 

 on silver after the manner of medallic relief, and then floating it over 

 with variously coloured transparent pastes. The fourth, or Jeuxllcr't 

 style, was either actually invented by Benvenuto Cellini, or he at 

 least was the first to describe the improvement that took place in the 

 enamelling art about the beginning of the 16th century. This method 

 consisted in the use of a particular vehicle or liquid with the glass 

 powder employed to cover small gold or silver objects in the round or in 

 very high relief ; the vehicle consisted of water in which the pips of 

 pears had been steeped ; the paste was held in its place until vitrifi- 

 cation took place, and was yet so delicate a cement as in no degree to 

 interfere with the perfect purity of the enamel The fifth, or Late 

 Limoges style, sprang at once from the inventive genius of Leonard 

 Limousin, under the auspices of Francis I. It differed from the pre- 

 ceding styles chiefly in this : that the surface of the metal was entirely 

 covered with an opaque paste, on which paintings were executed in 

 transparent colours ; the effect of a translucent ground was then 

 obtained by applying silver leaf in particular situations, fixing it with a 

 glaze of coloured enamel, and finally tinting over it. In the hands of a true 1 

 artist, this method was susceptible of beautiful results ; but it degene- 

 rated into tawdriness under the Nouailhers, a family of enamellers who 

 lived during the latter part of the 17th century. The sixth, or Miniature 

 style, was that which Petitot, the cnameller mentioned in the last 

 paragraph, was the first to bring to a high state of excellence. The 

 chief characteristics of this style were, a great enrichment by tin- 

 addition of new pigments, a power of multiplying the immlT "I 

 firings, a more minute graduation of tint*, and an increasing nmdiii- 

 cation in hardness and fusibility by means of fluxes. This, in t In- 

 present day, is the chief kind of enamel-work, considered as a bmnrh 

 of the fine arts. 



The painting on enamel is in it-Hf virtually enamelling; for the- 

 pigment employed is mi rn.uni], m x\sw, or vitrifiable substance, 

 coloured with various metallic oxides, chlorides, and salts (no vegetable 

 or animal colours being employed). The coloured pieces of enamel are 

 ground up very finely in an agate mortar with oil of lavender, or some 

 other liquid ; and the paint thus prepared is laid on with a fine camel- 



