water glass or soluble glass, colorless, transparent, glasslike substance available commercially as a powder or as a transparent, viscous solution in water. Chemically it is sodium silicate, potassium silicate, or a mixture of these. It is prepared by fusing sodium or potassium carbonate with sand or by heating sodium or potassium hydroxide with sand under pressure. Water glass is very soluble in water, but the glassy solid dissolves slowly, even in boiling water. Water glass has adhesive properties and is fire resistant. It is used as a detergent; as a cement for glass, pottery, and stoneware; for fireproofing paper, wood, cement, and other substances; for fixing pigments in paintings and cloth printing; and for preserving eggs (it fills the pores in the eggshell, preventing entrance of air).

stained glass, in general, windows made of colored glass. To a large extent, the name is a misnomer, for staining is only one of the methods of coloring employed, and the best medieval glass made little use of it.

Background

Colored glass as window decoration is of great antiquity in East Asia. Muslim designers fitted small pieces of it into intricate window traceries of stone, wood, or plaster, and this type of window mosaic is still in use. Colored glass was used in windows of Christian churches as early as the 5th cent., and pictorial glass as early as the 10th cent.

Medieval Stained Glass

With the development of medieval architecture, stained glass assumed a unique structural and symbolic importance. As the Romanesque massiveness of the wall was eliminated, the use of glass was expanded. It was integrated with the lofty vertical elements of Gothic architecture, thus providing greater illumination. Symbolically, it was regarded as a manifestation of divine light. In these transparent mosaics, biblical history and church dogmas were portrayed with great effectiveness. Resplendent in its material and spiritual richness, stained glass became one of the most beautiful forms of medieval artistic expression.

The early glaziers followed a sketched cartoon for their window design. They used a red-hot iron for cutting the glass to the required pieces, afterward firing in the kiln those that had received painted lines and shadings. The pieces were then fitted into the channeled lead strips, the leads soldered together at junction points, and the whole installed in a bracing framework of iron called the armature. The lead strips were adjusted to the articulation of the design and formed an integral part of it. The coloring of glass was achieved in the melting pot, where metallic oxides were fused with the glass. The metallic ores, although at first crude and limited, ultimately produced admirable color variations. The glass, available only in small pieces, gave thereby a jewellike quality to the colors. The pieces, by their uneven surfaces and varying thicknesses, gave the advantage of irregular and scintillating refractions of light.

Only fragments remain of glass from the 11th cent. The period of greatest achievement in the art extended from 1150 to 1250. Some examples from the 12th cent. can be seen in the windows of Saint-Denis (Paris), Chartres, and Le Mans in France, as well as at Canterbury and at York Minster in England. The windows of this period were characterized by rich dark colors, single figures, and scrollwork. A recurrent design, that of the Jesse tree, continued in use until the 16th cent.

By the beginning of the 13th cent. figures were abundantly used in scenes, being enclosed in geometrical medallions, such as circles, lozenges, or quatrefoils. A window was composed of many of these medallions. Color became more detailed and varied, and the prevailing scheme of red, blue, green, and purple, with small amounts of white, created tense and vibrant harmonies. In France the cathedral at Chartres is an unrivaled treasury of 13th-century glass; Sainte-Chapelle, Paris, is a triumph of architecture in which the walls present an illusion of being made entirely of fragile, exquisite stained glass. In England there are outstanding windows at York, Lincoln, and Salisbury. In the 14th cent. as medieval glass-making waned, medallion compositions were replaced by a single figure framed in canopied shrines. Many windows showed clear areas designed in grisaille.

See also rose window.

Later Stained Glass

In the 15th cent. glass artists achieved a silvery tone by the use of large proportions of white glass, and their figures of saints and apostles were surmounted by elaborate canopies. With improved glassmaking many of the assets of medieval stained glass (small, jewellike pieces of varying thicknesses) vanished. By the 16th cent. the material was smoother and in larger pieces; toward the middle of this century the use of enamel paints permitted the designs to be entirely painted on the glass and then fired. During the 16th cent. stained glass designers emulated the purely pictorial effects of Renaissance oil painting, with complicated perspectives, large scale, and realistic detail.

Stained Glass in the Modern World

Nineteenth-century romanticism and the Gothic revival brought fresh study and emulation of stained glass as well as of other medieval arts. The arts and crafts movement under William Morris was especially productive. A great contribution to American stained glass was made by John La Farge and Louis Comfort Tiffany. In modern art the medium has been used with great effectiveness by Rouault, Matisse, and Chagall.

soluble glass: see water glass.

opera glass: see binocular.

magnifying glass: see microscope.

glass snake, common name for the snakelike legless lizards of the genus Ophisaurus found in the S and central United States and in Eurasia. The shiny, scaled body is gray or greenish brown, sometimes striped above and whitish below. The American species, Ophisaurus ventralis, is 2 to 3 ft (60-90 cm) long; two thirds of the length is tail. The tail of a glass snake breaks easily from the body, either whole or in pieces, if struck; the lizard regenerates a new, usually shorter, tail without a real backbone. Like other lizards, and unlike snakes, the glass snake has eyelids and ear openings. Its tongue is broad. It feeds mostly on insects, worms, and slugs. A burrower, it lives in fields and meadows and seldom appears above ground in daylight. Glass snakes are classifed in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Anguidae.

glass harmonica: see harmonica 2.

glass fiber: see fiberglass.

glass, hard substance, usually brittle and transparent, composed chiefly of silicates and an alkali fused at high temperature.

Composition and Properties of Glass

Most glass is a mixture of silica obtained from beds of fine sand or from pulverized sandstone; an alkali to lower the melting point, usually a form of soda or, for finer glass, potash; lime as a stabilizer; and cullet (waste glass) to assist in melting the mixture. The properties of glass are varied by adding other substances, commonly in the form of oxides, e.g., lead, for brilliance and weight; boron, for thermal and electrical resistance; barium, to increase the refractive index, as in optical glass; cerium, to absorb infrared rays; metallic oxides, to impart color; and manganese, for decolorizing. The term "crystal glass," derived from rock crystal, was at first applied to clear, highly refractive glass; it has come to denote in the trade a high-grade, colorless glass and is sometimes applied to any fine hand-blown glass.

The Process of Glassmaking

The processes of glassmaking have remained essentially the same since ancient times. The materials are fused at high temperatures in seasoned fireclay containers, boiled down, skimmed, and cooled several hundred degrees; then the molten glass (called metal) is ladled or poured into molds and pressed, or is blown (sometimes into molds), or is drawn. The shaped glass is annealed to relieve stresses caused by manipulation, then is slowly cooled. The glass, formerly annealed on shelves in a melting furnace, is now usually carried on rollers through annealing ovens (lehrs).

Although today most hollow vessels such as light bulbs or containers are machine blown, fine ornamental hollow ware is still made by gathering a mass of glass at the end of a long, iron blowpipe, blowing it into a pear-shaped bulb, which is rolled on an oiled slab (marver), shaped with tools, and then reblown, often into a mold; the glass is reheated periodically in a small furnace (glory hole). It is finally transferred to an iron rod (punty) attached to the base of the vessel, and the lip is shaped and smoothed. Methods of decoration include cutting, copper-wheel engraving, etching with hydrofluoric acid, enameling, gilding, and painting.

Development of the Glass Industry

Humans have used glass since prehistoric times, at first fashioning small objects from natural glass such as obsidian, a volcanic glass, or from rock crystal, a colorless, transparent quartz whose brilliance and clarity are emulated in manufactured glass.

Ancient Glassmaking

The place and date of origin of manufactured glass are not known. The oldest known specimens of glass are from Egypt (c.2000 B.C.), where the industry was well established c.1500 B.C. Many varieties of glass were known during Roman times, including cameo glass, such as the Portland vase, and millefiore glass, produced from fused and molded bundles of thin glass rods of many colors. Glass was also used for window panes, mirrors, prisms, and magnifying glasses. Except for the work done in Constantinople, little is now known of the methods of glassmaking used in Europe from the fall of Rome until the 10th cent., when stained glass came into use.

Early European Glassmaking

Venice was the leader in making fine glassware for almost four centuries after the Crusades and attempted to monopolize the industry by strict control at Murano of glassworkers, who were severely penalized for betraying the secrets of the art. After the invention (c.1688) of a process for casting glass, France was for many years supreme in the manufacture of plate glass such as that used to line the Galerie des Glaces at Versailles. Late in the 17th cent. England began to make flint glass, whose lead oxide content imparted a brilliance and softness that made it suitable for cut glass.

Glassmaking in Colonial America

The first glass factory in America was built in 1608, and glass was carried in the first cargo exported to England. Although other glasshouses were operated in the colonies, especially in New Amsterdam, the first successful and enduring large-scale glasshouse was set up by the German-born manufacturer Caspar Wistar in New Jersey in 1739. Some of the finest colonial glassware was produced in the Pennsylvania glasshouses of the German-born manufacturer H. W. Stiegel.

Beginnings of the Modern Era

The invention of a glass-pressing machine (c.1827), used by the American manufacturer Deming Jarves in his Boston and Sandwich Glass Company (1825-88), permitted the manufacturing of inexpensive and mass-produced glass articles. Nevertheless, in the 19th and 20th cent., there has remained a sense of pride in individual craftsmanship. The American artist Louis C. Tiffany was responsible for the design and manufacture of an extraordinary iridescent glass used in a variety of objects in the late 1800s. Exceptionally fine blown glassware has been designed by such artists as René Lalique and Maurice Marinot in France, Edvard Hald and Simon Gate in Sweden, as well as Sidney Waugh in the United States.

Contemporary Applications of Glass

Glass has become invaluable in modern architecture, illumination, electrical transmission, instruments for scientific research, optical instruments, household utensils, and even fabrics. New forms of glass, new applications, and new methods of production have revolutionized the industry. Recently developed forms of glass include safety glass, which is usually constructed of two pieces of plate glass bonded together with a plastic that prevents the glass from scattering when broken; fiberglass, which is made from molten glass formed into continuous filaments and used for fabrics or for electrical insulation; and foam glass, which is made by trapping gas bubbles in glass to yield a spongy material for insulating purposes. Certain uses of glass are now being superseded by newly developed plastics.

See also window.

field glass: see binocular.

Venus's looking-glass: see bellflower.

Glass, Philip, 1937-, American composer, b. Baltimore. Considered one of the most innovative of contemporary composers, he was a significant figure in the development of minimalism in music. Glass attended the Juilliard School of Music (M.A., 1962) and studied (1964-66) with Nadia Boulanger in Paris. There he also met Indian musicians Ravi Shankar and Alla Rakha, whose music was to influence his own compositions strongly. In 1968 he formed the Philip Glass Ensemble, a small group that employs electronically amplified instruments. During the 1970s he became known for music that blended standard notation and tonality with electronics. These lengthy and highly rhythmic compositions employ a number of phrases that are repeated and slowly modified during the music's course. The purest form of this style is represented in the four-hour-long Music in 12 Parts (1971-74).

More traditional harmonies entered his work with the opera Einstein on the Beach (1976), which Glass wrote with Robert Wilson; a work introduced the minimalist style to a mass audience and paved the way for a wider acceptance of contemporary opera. The meditative Einstein is without narrative plot and blends light, image, and sound as well as dance, words, and music into a hypnotic whole. During the ensuing years Glass's work has become more complex and varied. His best-known works are his operas; Satyagraha (1980), Akhnaten (1984), The Fall of the House of Usher (1988), Hydrogen Jukebox (1990, a collaboration with Allen Ginsberg), The Voyage (1992), and La Belle et la Běte (1994, composed for Jean Cocteau's film) followed Einstein. Three had their American debuts in 2001—The Marriages between Zones 3, 4 and 5 (1997); the epic White Raven (1998), another collaboration with Robert Wilson; and the smaller-scale In the Penal Colony (2001), based on the Franz Kafka short story. Later operas are Galileo Galilei (2002); Waiting for the Barbarians (2005), based on a novel by J. M. Coetzee; and Appomattox (2007), which dramatizes the American Civil War's last weeks and its aftermath. Glass's other compositions include symphonies, concertos, string quartets, songs, and film scores. Glass's work has been extremely influential in the development of a new generation of composers.

Glass, Montague Marsden, 1877-1934, American humorist and playwright, b. England, educated at the College of the City of New York and at New York Univ. He won fame for his humorous delineations of American Jewish life and character, especially in the "cloak and suit trade." Potash and Perlmutter (1910) and Abe and Mawruss (1911) were both successful as magazine stories and later as plays.

Glass, Carter, 1858-1946, American politician, U.S. Secretary of the Treasury (1918-20), U.S. Senator from Virginia (1920-46), b. Lynchburg, Va. He learned the printer's trade and became owner of the Lynchburg Daily News and Daily Advance. Glass became prominent in local politics, then served (1902-18) in the House of Representatives. As chairman of the House Committee on Banking and Currency, he was active in the framing of the Federal Reserve System. In 1918 he became Secretary of the Treasury under President Wilson, but in 1920 he resigned to become Senator from Virginia by appointment. Elected Senator for the balance of the term, he was reelected four times, serving until his death. He violently opposed President Franklin Delano Roosevelt's monetary and New Deal policies, but supported Roosevelt's foreign policy.

Any glassy rock formed from lava or magma that has a chemical composition close to that of granite. Such molten material may reach very low temperatures without crystallizing, but its viscosity may become very high. Because high viscosity inhibits crystallization, the combination of sudden cooling and loss of volatiles, as when lava extrudes from a volcanic vent, tends to chill the material to a glass rather than crystallize it.

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Coloured glass used to make decorative windows and other objects through which light passes. Stained glass is often made in large, richly detailed panels that are set together in a framework of lead. Like all coloured glass, it acquires its colour by the addition of metallic oxides to molten glass. A purely Western phenomenon, stained glass originated as a fine art of the Christian church, beginning in the 12th–13th century, when it was combined with Gothic architecture to create brilliant, moving effects. A decline set in after the 13th century, when stained-glass artists began to seek the realistic effects sought by Renaissance painters, effects to which the technique was less suited and which diverted artists from exploiting the all-important light-refracting quality of glass. More recently, stained-glass artists have again achieved high quality: during the 19th-century Gothic revival, in the Art Nouveau designs of Louis Comfort Tiffany, and in the work of such 20th-century artists as Marc Chagall.

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or glass fibre

Fibrous form of glass, developed in the 1930s. Liquid glass issues in fine streams through hundreds of fine nozzles, and the solidifying streams are gathered into a single strand and wound onto a spool. Strands can be twisted into yarns, woven into fabrics, or chopped into short pieces and then bonded into mats. Glass filaments and yarns add strength and electrical resistivity to molded plastic products. Glass fabrics are used as electrical insulators and as reinforcing belts in automobile tires. Discontinuous fibres are formed into wools, mats, or boards, commonly used in buildings, appliances, and plumbing.

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Solid material, typically a mix of inorganic compounds, usually transparent or translucent, hard, brittle, and impervious to the natural elements (“vitreous properties”). It is made by cooling molten ingredients fast enough so no visible crystals form. A poor conductor of heat and electricity, glass takes on colours when certain metal oxides are included in the mix. Most glass breaks easily. Obsidian is a naturally occurring glass. Everyday glass (soda-lime or soda-lime-silica) is made of silica (silicon dioxide), soda (sodium carbonate), and limestone (calcium carbonate), with magnesia (magnesium oxide) for sheet glass or alumina (aluminum oxide) for bottle glass. Fused silica is an excellent glass but expensive because of pure silica's very high melting point. Borosilicate glass (e.g., Pyrex) is used for cookware and laboratory glassware because it expands very little when heated. Lead crystal is used for fine tableware. It has a heavy feel because of its lead oxide content and a sparkle due to its high refraction index. Even more specialized glasses include optical, photosensitive, metallic, and fibre-optic. Since glass has no sharp melting point, most types can be shaped while hot and plastic by many techniques, mostly blowing or molding. Seealso volcanic glass.

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(born Jan. 31, 1937, Baltimore, Md., U.S.) U.S. composer. He studied mathematics and philosophy at the University of Chicago and then studied composition at the Juilliard School and with Nadia Boulanger in Paris. His later studies with the Indian sitarist Ravi Shankar in 1966 and the tabla player Alla Rakha produced a radical shift in his compositional style. He became the leading exponent of musical “minimalism,” employing insistently repeated notes and chords, subtly shifting timbres, and blocklike harmonic progressions without contrapuntal voice leading. He achieved fame suddenly with the opera Einstein on the Beach (1975) and went on to write more than 20 operas, including Satyagraha (1980), Akhnaten (1984), and The Voyage (1992). His other works include many film scores, such as Koyaanisqatsi (1983) and The Thin Blue Line (1988), and the recordings Glassworks (1981) and Songs from Liquid Days (1986). He collaborated with a wide range of writers, artists, and musicians, including Robert Wilson, Allen Ginsberg, Doris Lessing, David Bowie, and Paul Simon. Glass's work appealed to fans of rock and popular music, and at the turn of the 21st century he was perhaps the world's most famous living composer.

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(born Jan. 4, 1858, Lynchburg, Va., U.S.—died May 28, 1946, Washington, D.C.) U.S. politician. Largely self-educated, he pursued a successful career in journalism, eventually becoming proprietor of two Lynchburg newspapers. In the U.S. House of Representatives (1902–18), he sponsored legislation that established the Federal Reserve System. As secretary of the treasury (1918–20) he supported efforts by Pres. Woodrow Wilson to bring the U.S. into the League of Nations. Appointed, then elected, to the U.S. Senate (1920–46), he became a leader of the conservative Southern Democratic bloc. An expert on monetary policy, he coauthored legislation that established the Federal Deposit Insurance Corp. (FDIC) in 1933. Though he supported Franklin Roosevelt for president in 1932, he soon became one of his sharpest critics.

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