Page:The New International Encyclopædia 1st ed. v. 07.djvu/71

* EMULSIN. 55 milk). An enzyme found in plants, which de- composes various glucosides into glucose (grape- sugar) and other products. It occurs in cei tain members of the rose family, notably in the almonds, both sweet and bitter, and the cherry laurel, in some spurges belonging to the genua Manihot, and in several common mollis and li chens. Amygdalin, salicin, and other glucosides are split up by emulsin, which acts best in neu- tral solutions and at temperatures between 30° and 40° C. (80° and 104° F.). It is destroyed at about 80° C. (176° F.i. See Enzyme; Glu- coside; Almonds, Volatile Oil of. EMULSION (Fr. emulsion, from Lat. .,„»/ ffere, to milk out). The term applied to those preparations in pharmacy obta ined by triturating certain substances with water, and where the product is a milky-white, opaque mixture of a 'gummy consistence, and composed more or less of oily particles floating in mechanical suspen- sion in the mucilaginous liquid. ENAL'IDS (from Ok. h>, en, in + as, hals, sea). In botany, the members of the marine fixed vegetation (benthos) (q.v.) which grow at- tached to loose soil. Submerged eel-grass mead- ows form one of the chief enalid societies. ENAL'IOSAU'RTJS. Plesiosatjbtjs. ENAMEL. See Ichtiitosaurus ; ENAMBUC, a'naN'huk', or ESNAMBTJC, Pierre Vaxdeosque Diel d' (c.1570-1636). A French navigator and founder of the French settlements in the West Indies. He was born at' Dieppe, and as commander of a vessel in the Caribbean took possession of the island of Saint Christopher for the purpose of colonization. A plan suggested by him to the governments of France and England, whereby the island was to be divided between the two countries, was ap- proved, and in 1626 d'Enambuc transported more than 500 immigrants to the new possession. Afterwards he established settlements on Mar- tinique and other islands of the Caribbean. The town and fort of Saint Pierre, completely de- stroyed by a volcanic eruption, May 8, 1002, were founded by him. ENAMEL (ere + older form amel, Fr. 6mail, OF. esmail, It. smdlto, from OHO. smalz, Ger. Schmalz, butter, from sehmelzen, to melt, Gk. /liTidetv, meldein, to melt). A glaze coating ap- plied by fusion to any substance which will bear the necessary heat, especially to metals and to pottery (q.v.). Enamel is really a kind of glass, and although it is usually of special composition, in order to produce an easily fusible material, the name is applied rather to glass when used in certain special ways. In (lie purely utili- tarian employment of enamel, its purpose is to protect the surface to which it is applied from the action of corrosive substances. Thus, the liability of iron to oxidation when exposed to heat or moisture, and to corrosion by even the weakest acids, has led to many attempts to coat it with a protecting surface. For this purpose coatings of various materials have been employed (see Iron), but the most efficient has been found to be enamel. The earlier enameled ware was usually thick, but enamel is now successfully ap- plied to sheet iron and sheet steel. The utensils are pressed out of the sheet metal according to the process described under Oiks and DlE-SlNK ixg, and under Hollow Ware. The metal foundation having been properly prepared by annealing to stand the heal, it is dipped in the melted glaze and fired in an oven simifai to that employed for the glazing of pottery, which is kept at a temperature ol about 1500' F. The constituents of the glaze and their proportions vary in the dillerenl factorie. and are carefully guarded trade secrets. The color of enameled ware- is determined by the metallic oxides used in the glaze, and does not materially alter the character of the enamel, although a pure white enamel is likely to be less tough than gray. The quality of the enamel depends not only on the character of the glaze, but also upon the number of coats applied. By one process four successive coats are applied, the first three of which are simply dried, while the fourth is binned at 1500° F. In another, two successively fused coats are applied. In the cheaper grades of enamel- ware arsenic is said to be used in place of the oxide of tin, thus decreasing the cost, according to the statement of a leading manufacturer, by 75 per cent. Agate ware is simply a trade name for a variety of enameled ware, so called on ac- count of its mottled appearance. Enameled ware, even of the highest grade, is likely to be injured by excessive heat, which, by making the iron expand faster than the glaze, cracks the latter. It is also liable to be affected by acids wherever there is the slightest break in the con- tinuity of the surface of the enamel. When once acid penetrates the surface so it can act on the iron underneath, it. will gradually undermine the glaze so that it, peels off. Enamel in Ceramics. In ancient European practice the material was. and in modern Orien- tal practice it still is, sometimes applied so as to cover the whole surface, and the new surface thus formed may be painted with vitrifiable colors, or the enamel may be applied to parts of the surface only, so that the colors of this partial application, combining with the colors of the object itself, may produce a decorative effect; and. finally, the enamel may, be treated as a trans- parent or translucent mass, showing its color effect equally by transmitted and by reflected light. In each of these methods the enamel itself is provided in lumps, or sticks, or rods, each piece being usually of a separate solid color. This material is ground very fine, mixed with gum water or some similar adhesive vehicle until it forms a paste, and can be applied with a brush. The object is then put into the enameling furnace, and in the heat the enamel passes from the con- dition of a dampened powder, through the state of flux or semi-fluidity, into a hard, glossy, bubble-like mass looking very like the wet powder of its first condition. Modern glass of brilliant iridescent surface is not generally enameled : but the glass lamps sus- pended in mosques throughout the Levant, and the glass vases, drinking-vessels and the like, which are also of Saracenic or Moorish work, are decorated by enameling in the proper sense. The distinction is obvious to one who notes that, in the Oriental pieces, the body of the glass vessel shows between the usually opaque and pro- jecting masses of the enamel which has been put on separately and fused and hardened separately. Similar work has been done in Europe, though rarely. So in a porcelain vase decorated in colors, the painting which is applied over the glaze i- of the nature of enameling, and is easily