ENA 



ENA 



most common species in Europe is the 

 E. livida, which is a brownish fly ; the 

 wi?igs are transparent, with dark veins. 

 They are obst rved in fields and gardens. 

 E. borealis is of a more slender form 

 than the common window fly, and of a 

 blackish colour, with large, broad, oval 

 wings, of a brown colour, and rurous legs 

 varied with black. 



EMPLASTRUM, in pharmacy, a com- 

 position for external use, generally spread 

 upon leather, linen, or some other con- 

 venient thing, before it is applied. See 

 PHARMACY. The following is a re- 

 cipe for makihg the Ladies Court Plas- 

 ter : " Dissolve five ounces of isinglass 

 in a pint of water, and having ready a 

 quantity of thin black sarsenet, stretched 

 in a proper frame, apply the solution 

 warm with a brush equally over the sur- 

 face. This is to be rep -ated, after it is 

 dry, two or three times." Some give it 

 a coat of gum benzoin dissolved in al- 

 cohol ; but this is injurious rather than 

 beneficial. 



EMI LEURUM, in botany, a genus of 

 the Monoecia Tetrandna class and or- 

 der. Natural order of Aggregate. Ru- 

 tacese, Jussieu. Essential character : 

 male, calyx four-cleft ; corolla none : fe- 

 male, calyx four-cleft, inferior ; corolla 

 none ; stigma cylindric, placed on the 

 lateral toothlet of the germ ; capsule 

 opening on the side ; seed one, anlled. 

 There is but one species ; viz. E. ser- 

 rulatum, Cape empleurum. This is a 

 shrub, with wand-like, even branches ; 

 leaves like those of a willow, alter- 

 nate, subpetioled, linear-lanceolate, even 

 above, beneath longitudinally wrinkled ; 

 peduncles few-flowered, lateral, much 

 shorter than the leaves ; flowers small, 

 most of them male ; capsules usually so- 

 litary, incurved with a beak of the same 

 length. 



EMULSION, a milky looking fluid, 

 caused by an imperfect combination of 

 oil with water, by means of mucilage, 

 gluten, &.c. All oily farinaceous seeds, 

 as nuts, almonds, linseed, &c. form an 

 emulsion by tnturation with water ; yolk 

 of egg, which is a natural compound of 

 oil ana albumen, makes a similar emul- 

 sion. 



ENAMELLING. Neri on glass, with 

 the notes of Merret and Kunckel, afford 

 a variety of good receipts for making 

 enamels, though much still remains to 

 be done in this art. The art is indeed 

 retarded by the considerable advantages 

 the enameller derives from the discovery 



of any colour uncommonly brilliant;, clear, 

 or hard. On this account the artist na- 

 turally endeavours to keep his process a 

 secret, as the source of private gain. 

 The principal ingredients of enamel co- 

 lours are, however, weil known. 



There are two kinds of enamel ; the 

 opaque and the transparent. Transparent 

 enamels are usually rendered opaque 

 by adding putty, or the white oxide of 

 tin, to them. The basis of all enamels 

 is therefore a perfectly transparent and 

 fusible glass. The oxide of tin renders 

 this a oeautiful white, the perfection of 

 which is greater when a small quantity 

 of manganese is likewise added. If the 

 oxide of tin be not sufficient to destroy 

 the transparency ot the mixture, it pro- 

 duces a semi-opaque glass, resembling 

 tiie opal. 



Yellow enamel is formed by the addi- 

 tion oi oxide of lead or antimony. Kunc- 

 kel likewise affirms that a beautiful yel- 

 low may be obtained from silver. 



Red enamel is formed by the oxide of 

 gold, and also by that of iron. The for- 

 mer is the most beautiful, and stands 

 the fire, which the latter does not. 



Oxide of copper affords a green, man- 

 ganese a violet, cobalt a blue, and iron a 

 very fine black. A mixture of these ena- 

 mels produces a great variety of inter- 

 mediate colours, according to their na- 

 ture and proportion. In this branch of 

 the art the coloured enamels are some- 

 times mixed with each other, and some- 

 times the oxides are mixed before they 

 are added to the vitreous bases. 



The enamelier who is provided with a 

 set of good colours is very far from being 

 in a situation to practise the art, unless 

 he be skilled in the methods of applying 

 them, and the nature of the grounds up- 

 on which they are to be laid. Many of 

 the metals are too fusible to be enamel- 

 led, and most of them are corroded by 

 the action of the fused glass. For this 

 reason none of the metals are used but 

 goid, silver, and copper. Platina has in- 

 deed been used ; but of its effects and 

 habitudes with enamel very little can be 

 said, for want of a sufficient number of 

 experiments. 



The purest gold, of 24 carats, is calcu- 

 lated to produce the best effect with ena- 

 mel. 1. Because it entirely preserves 

 the metallic brilliancy, without undergo- 

 ing any oxidation in the fire. 2. Being 

 less fusible, it will admit of a more re- 

 fractory, and consequently a harder and 

 more beautiful enamel. It is not usual. 



