446 EQUIVALENTS, CHEMICAL.

The enamelling workshop ought to admit little or no daylight, otherwise the artist, notperceiving his flame distinctly, would he apt to commit mistakes.

It is impossible to describe all the manipulations of this ingenious art, over whichtaste and dexterity so entirely preside. But we may give an example. Suppose theenameller wishes to make a swan. He takes a tube of white enamel, seals one ofits ends hermetically at his lamp, and while the matter is sufficiently hot, he blows onit a minikin flask, resembling the body of the bird; he draws out, and gracefully bendsthe neck; he shapes the head, the beak, and the tail; then, with slender enamel rodsof a proper color, he makes the eyes; he next opens up the beak with pointedscissors; he forms the wings .and the legs; finally attaching the toes, the bird standscomplete.

The enameller also makes artificial eyes for human beings, imitating so perfectly thecolors of the sound eye of any individual, as to render it difficult to discover that he has.a blind and a seeing one.

It is difficult to make large articles at the blowpipe; those which surpass 5 or 6 inchesbecome nearly unmanageable by the most expert workman.

EPSOM SALTS . Sulphate of Magnesia.

EQUIVALENTS, CHEMICAL. ( Stochiomelrie , Germ.) This expression was firs!employed by Dr. Wollaston, to denote the primary proportions in which the variouschemical bodies reciprocally combine; the numbers representing these proportionsbeing referred to one standard substance of general interest, such as oxygen or hydrogenreckoned unity, or 1,000. Dr. Dalton, who is the true author of the grand discoveryof definite and multiple chemical ratios, calls these equivalent numbers atomic weight*}when reduced to their lowest terms, either hydrogen or oxygen being the radix of thescale. Though it belongs to a chemical work to discuss the principles and develop tl* eapplications of the Atomic Theory, I shall be careful, upon all proper occasions, topoint out the vast advantages which the chemical manufacturer may derive from it, ® nato show how much he may economize and improve his actual processes by its means-See Element.

ESSENCES are either ethereous oils, in which%11 the fragrance of vegetable productsreside; or the same combined and diluted with alcohol. See Oils, Ethereous.

ESSENCE D’ORIENT, the name of a pearly looking matter procured fromblay or bleak, a fish of the genus cyprinus. This substance, which is found princip® 1 .at the base of the scales, is used in the manufacture of artificial pearls. A large q oaa 'tity of the scales being scraped into water in a tub, are there rubbed between the hanto separate the shining stuff, which subsides on repose. The first water being decante >more is added with agitation till the essence is thoroughly washed from all impu rltl< ! s ’when the whole is thrown upon a sieve; the substance passes through, but the scaleare retained. The water being decanted off, the essence is procured in a viscid state, 0a bluish white color, and a pearly aspect. The intestines of the same fish are a scovered with this beautiful glistening matter. Several other fish yield it, but in , snJaJ 0 yproportion. When well prepared, it presents exactly the appearance and reflect 10 ” 8the real pearls, or the finest mother of pearl; properties which are probably owing 10^ interposition of some portions of this same substance, between the laminse ol

shelly concretions. Its chemical nature has not been investigated; it putrefies re 0 .when kept moist, an accident which may, however, b“ counteracted by water of ania. See Pearls.' , ,. ,j,is

ETCHING Varnish. (detzgrund-Deckfirniss , Germ.) Though the practice ° ^ ar ,elegant art does not come within the scope of onr Dictionary, the preparation of tilnishes, and of the biting menstrua which it employs, legitimately does. . ,, oWS :

The varnish of Mr. Lawrence, an English artist resident in Paris , is made as -itch *Take of virgin wax and asphaltum, each two ounces, of black pitch and burgun y^each half an ounce. Melt the wax and pitch in a new earthenware glazed pot, a t j W eto them, by degrees, the asphaltum, finely powdered. Let the whole boil till s °as that, taking a drop upon a plate, it will break when it is cold, on bending 1 petwo or three times betwixt the fingers. The varnish, being then enongh boiled, jna ytaken off the fire, and after it cools a little, must be poured into warm water t a bework the more easily with the hands, so as to be formed into balls, whichkneaded, and put into a piece of taffety for use. - Rirnin" **‘5

Care must be taken, first, that the fire be not too violent, for fear of baltd® ’ singredients, a slight simmering being sufficient; secondly, that whilst the as P ^ c<> 0 ~putting in, and even after it is mixed with the ingredients, they should be su ; tio n 18tinually with the spatula; and thirdly, that the water into which this c ° rop ven t athrown should be nearly of the same degree of warmth with it, in order o Pkind of cracking that happens when the water is* too cold. _ . n( j jt wifi

The varnish ought always to be made harder in summer than in winter,snhaltu 111 otbecome SO if it be suffered to boil longer, or if a greater proportion of the a I