ferin, daphnin, dhurrin, gentiopicrin, helicin, incarnatrin, indican, mandelonitrile glucoside, meliatin, oleuropein, picein, prulaurasin, salicin, sambunigrin, syringin, taxicatin and verbenalin, and the synthetic B-glucosides.

Emulsin is prepared by digesting the oil-free pulp of ground sweet almonds with a little toluene or chloroform for several hours, generally overnight. The whole is then put into a cloth bag and the liquid pressed out. This is treated with acetic acid, drop by drop, until the protein has been all precipitated. The clear liquid is treated with alcohol in repeated small quantities until no more precipitate falls. Pouring off the liquid the precipitate is hurriedly washed with absolute alcohol and ether to remove all moisture. It is then thoroughly dried in a vacuum to a soft white powder. Consult Armstrong, E. F., 'Lactase, Maltase and Emulsin' (London 1912).

EMULSION, the term applied to those preparations in pharmacy in which oily substances are suspended in water by means of gum, sugar, carrageen, etc., called emulsifiers. In general it will be found that the bulk of the emulsifier must first be taken, while the oil should only be added little by little, rubbing together in a mortar, and taking care that it is completely absorbed or emulsified before further additions. Should too much be added, the effect is to throw out most of what has already been incorporated; it is then practically impossible to remedy the error. The emulsion of cod-liver oil is familiarly known. Milk and the yolk of eggs are natural emulsions. The name is also given to suspensions in water of certain insoluble substances, such as resins. These being reduced to impalpable form are mixed with a syrup of gum or sugar, or other viscid fluid thick enough to prevent their settling. A familiar instance of this form of emulsion is common coal tar, which appears black because of the particles of free carbon suspended in the colorless pitch.

ENAMBUC, a-non-bük, or ESNAMBUC, Pierre, French navigator: b. Dieppe about 1570; d. Saint Christopher, W. I., December 1636. Being of an adventurous spirit, he sailed from Dieppe in 1625 in a brigantine of eight guns, for the Antilles. He landed in the island of Saint Christopher on the same day with a party of English colonists, with whom he divided the island, and, until his death, held the French half of the colony with extraordinary tenacity. In 1635 he took possession of Martinique, in the name of the king of France, and founded the town of Saint Pierre (q.v.).

The

ENAMELS AND ENAMELING. term enamel is used for certain siliceous compounds employed for coating metals. They are, in every sense of the word, glass, either transparent, opaque, white or colored. The art is a very ancient one, some claiming it originated with the Scythians, who are said to have introduced it into China during the reign of a certain Emperor Thaïwonti, but India was acquainted with the art before China. Extant evidence exists that the ancient Egyptians, Phoenicians and Assyrians used enamel coating in the decoration of jewelry, and of the clay beads and scarabs of the Nile-dwellers in our museums many are covered with colored glass. The subject of enamel work on the precious

metals is discussed in another article (see ART ENAMELS), So we will confine this article to the technical side of enamel production and the industrial utilization of enamel.

Raw Materials. The ingredients used in the production of the different kinds of enamels are felspar, quartz, fluorspar, borax, boric acid, soda, potash, saltpetre, cryolite, clays, ammonium carbonate, stannic oxide and water. The coloring agents used are cobalt oxide, limonite, iron oxides, chromic oxide, cupric oxide, etc. The felspar composition most desirable consists of siliceous earth 65 per cent, alumina 18 per cent, alkalis 16 per cent. For the creation of white enamels it is essential that the felspar shall be as free from iron oxide especially, as possible. Quartz must be pure but it is frequently replaced beneficially with a 'fine white river sand, which is pure quartz. Fluorspar or calcium fluoride of the purest quality only can be used, for white enamels especially. The borax needed for enamels is of the monoclinic system of crystallization (containing 10 molecules water of crystallization) not the octahedral crystals regular system, which contain only five molecules water. It is used as a flux or accelerator of fusion. Boric acid functions the same as borax but the former is more frequently used than the latter. Soda and potash have identical action in enamels and their presence heightens the lustre if it is not used too freely. The soda of commerce, being cheaper, is mostly employed; it is first calcined to obtain its anhydrous condition, then finely powdered, Saltpetre (nitre) used is the sodium variety, being cheaper than the potassium salt. It is used chiefly to decolorize; little or none at all is needed in the blue enamels. Cryolite used in the enamel industry may be either the natural or the artificial. This sodium-aluminum-fluoride is utilized for its double reaction of acting as flux and creating opalescence. Ammonium carbonate is supposed by some to be a valuable ingredient to inhibit cracking or crazing of the enamel in firing on account of its making the substance more uniform. Some authorities, however, declare its use a waste of money and useless. Stannic oxide is expensive with the present prices of tin but its use continues as a necessity after many attempts with substitutes. Care must be taken in maintaining the purity of the metal while in the oxidizing process or small black spots will appear in the baked enamel from impurities or may occur from particles of metal not having become oxidized. This chemical produces perfect opacity, which antimony substitutes do not, unless sufficient be used to cause other defects. The poisonous character of antimony has also caused its use to be forbidden in many countries. Lead oxide lends a wonderful brilliance to enamels; it acts also as a flux of great power. The lead oxides were formerly used considerably on earthenware utensils to assist the glaze, but long since they have been eliminated by law on account of their poisonous nature, their solubility rendering them extremely injurious when used on vessels for cooking, or even containing, foodstuffs. The use of the lead oxides is, therefore, restricted to the glazes of ornaments and art work.

Coloring Matters.- Cobalt oxide affords an intense blue color when used in strength and can be reduced in tone in lesser proportions.

Aside from its use in pigment cobalt oxide has the physical value of adhesiveness to sheet iron through its coefficient of expansion being the same as sheet iron. It, therefore, forms an ideal ingredient for the enamels used in cooking utensils. Perhaps it is here necessary to the uninitiated to state that one of the first requirements in an efficient enamel body is that it shall adhere to the metal under the stress of changes of temperature. On account of the high cost of cobalt nickel oxide is much used, through its considerably lower price. Limonite is a peroxide of manganese (called also pyrolusite) and is used in enamels to bleach out any impurity of tone in the white enamels. Additional proportions will produce dark violet (the noted manganese violet of the ceramist) and mixing a proportion of iron oxide with the limonite gives beautiful brown to black effects. Limonite in small proportions is sometimes blended with the more costly cobalt, producing a reddish blue of much brilliancy. Ferric oxide may be prepared to produce either a bright red or a reddish violet pigment according to the amount of heat applied in its manufacture. Chromic oxide produces a green enamel and cupric oxide gives a dark-green and a bluish-green; again a bluish-green can be obtained by a combination of copper and cobalt salts or chromium and copper salts, varying from bluish-green to greenish-blue according to their equivalents in the mixture. The salts of chromium, cadmium, uranium and titanium can each be used in obtaining yellow enamels. Ferrous chromate produces a lovely brown; it is called Brongniart's brown, after the great French ceramic chemist. Nickel is used in obtaining a gray enamel. The salts of gold produce a beautiful rose enamel as well as the loveliest pink. But a far less expensive pink is produced by chalk, quartz, stannic oxide, borax and bichromate of potash mixed and heated to a frit, the pigment being dissolved in water to separate it from the solids. Antimony produces several yellows including the noted Naples yellow (lead antimonate) of the art porcelains; they are, however, poisonous and forbidden in food utensils.

Enamel Manufacture.- In the mixing operations only absolutely trustworthy operators are employed. The working formulæ are kept strictly secret from all but the highest officials. From this point our description will be devoted to practices applied in the sheet iron and steel enamel industry. Every ingredient has to be dry and the degree of pulverization cannot be too fine to obtain a homogeneous enamel. The same care and time has to be given to the process of mixing the different ingredients. The French machine (mélangeur) does very effective work. The various chemicals are kept in separate bins, and, in order to maintain secrecy, each ingredient is known only under a letter or number. Taking the raw material from the bins it is loaded into small cars termed "dollies," which are loaded to a height approximating the quantity, then run on to a scale and weighed and the excess shoveled back or fresh added. The precaution is taken to have the scale beam and its graduation marks invisible to all but the person presiding over the work. With the completion of loading all the different materials in correct proportions in their individual "dollies" the material is mixed on a hard maple floor of the machine. First comes

the coarser material at bottom, the finest on top. The mixture made, it is hoisted by an electric elevator and run to its bin and the process is renewed in preparing the next kind of enamel, again to be stowed in its special bin. By means of a traveling bucket: holding the correct amount for a melt the mixed raw material (about 1,200 pounds) is carried to the blast furnace (rarely a crucible furnace). The kind of furnace common in American use is the same that is used in the manufacture of glass and is heated with natural gas or crude oil as the most economical fuel, though coal is used in the older factories. The furnace temperature has to be very carefully regulated as insufficient heat produces a slow melt liable to create a decomposition, whereas too high a degree may create combustion or some chemical reaction injurious to the outcome. Some authorities place 1,000° C. for a glaze heat and about 1,300° C. for a ground coat. Control over the heat is permitted by the installation of pyrometers. A furnace can afford from seven to eight melts in 24 hours. As the ingredients fuse separately according to their different melting points great care has to be taken that the mixed mass be kept stirred lest they separate. The length of time needed for the smelt differs according to the enamels, a white fusing well at two hours while ground enamels and blues take from two-and-a-half to three hours, and so forth. The enamel is now a liquid glass, in which state it is drawn off by releasing a fireclay plug located in the front of the furnace. The molten body flows into a tank of cold water and, with noisy reaction, the vitreous liquid is torn into shreds and small pieces with explosive violence, leaving minute fissures throughout the substance. Besides toughening the enamel body this so-called "quenching" assists in easing the next process, which is grinding. This grinding cannot be too fine, in fact the finer the resulting impalpable powder the brighter the resulting lustre of the enamel. The suddenly quenched glassy mass is known as a "frit." During the grinding other materials are added, such as stannic acid for creating an opaque white, or pigments for the different colors. About 30 hours is required for grinding in the large ball mills. The latter are cylindrical, about five feet in length and have a diameter of about six feet, and are lined with porcelain bricks. To the frit, which should retain about 50 per cent of water, is added a small percentage of white ball-clay. About 2 per cent zinc oxide improves a white. The clay addition is made to help hold the other ingredients in suspension, hindering them from subsiding according to their specific gravities; it also creates opacity, increasing at the same time, the needed quality of elasticity of the enamel. Other additions are added in proportions in accord with the secret formulæ, such as sal-ammoniac, ammonium-carbonate, magnesiumchloride, burnt magnesia, chloride of sodium (table salt), borax, soda, etc. The ground mass should reach the consistency of a rich cream, when it is poured into tanks and left to mature for a week or more.

Formulæ.-A German formula for a white enamel is (in kilogram equivalents) borax, 132; quartz, 152; felspar, 130; soda, 26; saltpetre, 6; cryolite, 78; fluorspar, 3; magnesia, 6. An asid-resisting enamel white is borax, 74;

felspar, 100; quartz, 115; cryolite, 47; stannic oxide, 40; fluorspar, 6; soda. 20; saltpetre, 10; magnesium carbonate, 1; pure powdered glassmeal, 53; clay, 12; calcspar, 6. A blue enamel formula is borax, 60.0; alumina, 3,6; felspar, 101.0; soda, 6.2; natural cryolite, 24.0; saltpetre, 3.0; fused enamel fragmentary, 40.0; cobalt oxide, 3.0; limonite, 0.3; ferric oxide, 0.1. A black fused enamel formula is borax, 62; felspar, 120; soda, 14; ferric oxide, 8; cobalt oxide, 2; smalt, 16; limonite, 16.

The Metal and Treatment.- In the production of steel enameled kitchen utensils the metal should be as free as possible from sulphur, carbon, silicon or phosphorus and with a general manganese content of about 0.2 per cent. The sheets (oblong or square) run from 27 to 20 gauge. Applying as little heat as possible, they are circled, stamped and spun, using a lubricant that is easily eliminated. A pickling process must, of course, cleanse the metal from impurities before the shaping is done. The additional trimmings (ears, handles, etc.) should be welded on because the enameling of riveted parts is a difficult process.

The Enameling Process. The operation as carried on in American factories is clearly described by R. D. Landrum, an expert. This work starts in the "dipping room," where the liquid enamel is placed in tanks of dish-pan form sunk into tables. The operator, called a "slusher," dips the stamped steel vessel (which has been previously cleansed of all grease' and impurities) into the enamel. Coming out of the immersion the vessel is covered with a film of the wet enamel, any drip or excess is eliminated by the slusher gently swinging the object, when it is placed, bottom down, on three metal points that project from a board. After several vessels are placed on the board it is set in a rack, and, when dry and the rack full, they are conveyed to the furnace room, where a bank of muffle ovens receives them. The temperature (about 1,000° C.) here fuses the minute powdered particles of enamel together into a glass coating covering the entire vessel, a process requiring but three to five minutes. Other coats are added, as needed, over this ground coat. In a three-coat piece we wish, perhaps, three coats of white on the inside and turquoiseblue outside. The ground coat enamel having dried and been passed through the oven comes out almost black, from the cobalt and nickel oxides, and the piece is left to cool. The slushing room operator now gives the vessel an immersion in white enamel and adds a black "bead" or edge on the rim. This second coat still shows up grayish as the first coat penetrates through after firing, so it is subjected to another dip at the hands of the slusher in the white enamel. A spray of blue-green enamel is applied to the outside, before drying, with the aid of a wire brush, or the more up-to-date machine which acts as an atomizer. The vessel is next dried and fired again in the oven, leaving turquoise blue spots outside on the white background. The next process is the assorting of the finished wares into "firsts," "seconds" and "thirds" or job lots, according to their perfection or defects. Imperfection in the cleaning of the original vessel may have caused minute spots to appear on the surface, due to rust or dirt. This defect can sometimes be remedied by filing the spots off, or subjecting them to a sand-blast,

and giving the vessel another coat of enamel. The discovery, or invention, of applying enamel coatings to metal ware such as kitchen utensils, bathtubs, etc., in the same manner as the bath tiles and earthen utensils which had been used by our fathers was indeed opportune, for the rising price of the metal had made the process of tinning so exorbitant that the industry was in real distress, with the certain prospect of the price of tin advancing to much higher proportions. The iron-enamel industry has extended its lines into sanitary ware, hygienic implements, chemical apparatus and numerous other branches. The growth of the industry, starting principally in France and Germany on a large scale, has extended to the United States, all in the course of about 25 years. The German output, by 1909 already, was 90,000,000 kilos, employing a capital of near $15,000,000. In 1914 the industry in Germany and AustriaHungary employed in the neighborhood of 60,000 wage earners. In the United States the "Census of Manufactures' (1914), gives us the following interesting statistics of the sheet iron and steel enamel industry. There were 270 factories, employing 28,731 operators. They produced goods valued at $68,979,005, and had a payroll of $15,242,586. Consult Gruenwald, J., The Theory and Practice of Enameling on Iron and Steel' (translation by H. H. Hodgson, London 1909); id., 'The Raw Materials for the Enamel Industry and their Chemical Technology (London 1914); Landrum, R. D., 'Enamels' (Cleveland 1918); Millenet, L. E., 'Manuel pratique de l'émaillerie sur métaux' (Paris 1917).

CLEMENT W. COUMBE.

ENARA, ä-nä'rā, or ENARE, ā-nä'rā, a lake in Finland; area, about 145 square miles. The outlet is Patsjoki River, which flows into the Arctic Ocean. A town of the same name, at the southwest extremity, is inhabited chiefly by fishermen.

ENAREA, ĕ-nä'rē-ä, a country of the Gallas, south from Abyssinia, between lat. 7° and 8° N., and long. 35° and 37° E. In the valley of the Gibbi, immediately beyond Sakha, the chief town of the country, are extensive plantations of coffee, which, along with ivory, is largely exported. The inhabitants are the most civilized of the Gallas, and show much skill in manufactures. Pop. about 40,000.

ENARGITE, en-är'jīt, a native sulpharsenate of copper, of which it contains 48.3 per cent. It constitutes an important ore of copper and is found in cleavable-granular masses, also in orthorhombic crystals. It has eminent prismatic cleavage, a brilliant metallic lustre, and grayish-black color and streak. Its hardness is 3 and specific gravity 4.44. It is common in Chile, Peru, Mexico, South Carolina, Colorado, Utah, California and Montana.

ENAULT, a'no, Louis, French novelist: b. Isigny, Calvados, 1824; d. Paris 1900. He used the pen-name "Louis Vermond." He wrote many novels and books of travel, including among them, 'Promenade en Belgique et sur les bords du Rhin' (1852); 'La terre sainte (1854); Constantinople et la Turquie' (1855); Voyage en Paponie et en Norvège' (1857); La Méditerranée, ses êles et ses bords' (1862); L'Amérique centrale et meridionale' (1866); 'Paris brûlé par la Commune) (1871);