regem, a treatise on astronomy and meteorology, which contained the sum of physical philosophy during the early middle ages. The Regula monachorum of Isidore was adopted by many of the monasteries in Spain during the 7th and 8th centuries. The collection of canons known as the Isidoriana or Hispalensis is not by him, and the following, attributed to him, are of doubtful authenticity: De ortu ac obitu patrum qui in Scriptura laudibus eferuntur; Allegoriae scripturae sacrae et liber numerorum; De ordine creaturarum.
The edition of all of Isidore's works by F. Orevalo (Rome, 1797–1803, 7 vols.), reproduced in Migne, Patrologia Latina, 81-84, is carefully edited. See also C. Canal, San Isidoro, exposicion de sus obras e indicaciones a cerca de la influencia que han ejercido en la civilization española (Seville, 1897). A list of monographs is in the Bibliographie of Ulysse Chevalier.
ISINGLASS (probably a corruption of the Dutch huisenblas, Ger. Hausenblase, literally "sturgeon's bladder"), a pure form of commercial gelatin obtained from the swimming bladder or sound of several species of fish. The sturgeon is the most valuable, various species of which, especially Acipenser stellalus (the seuruga), A. ruthenus (the sterlet) and A. giildenstddlii (the ossétr), flourish in the Volga and other Russian rivers, in the Caspian and Black Seas, and in the Arctic Ocean, and yield the "Russian isinglass"; a large fish, Silurus parkerii, and probably some other fish, yield the "Brazilian isinglass"; other less definitely characterized fish yield the "Penang" product; while the common cod, the hake and other Gadidae also yield a variety of isinglass. The sounds, having been removed from the fish and cleansed, undergo no other preparation than desiccation or drying, an operation needing much care; but in this process the sounds are subjected to several different treatments. If the sound be unopened the product appears in commerce as "pipe," "purse" or "lump isinglass"; if opened and unfolded, as "leaf" or "honeycomb"; if folded and dried, as " book, " and if rolled out, as " ribbon isinglass." Russian isinglass generally appears in commerce as leaf, book, and long and short staple; Brazilian isinglass, from Para and Maranham, as pipe, lump and honeycomb; the latter product, and also the isinglass of Hudson's Bay, Penang, Manila, &c., is darker in colour and less soluble than the Russian product.
The finest isinglass, which comes from the Russian ports of Astrakhan and Taganrog, is prepared by steeping the sounds in hot water in order to remove mucus, &c.; they are then cut open and the inner membrane exposed to the air; after drying, the outer membrane is removed by rubbing and beating. As imported, isinglass is usually too tough and hard to be directly used. To increase its availability, the raw material is sorted, soaked in water till it becomes flexible and then trimmed; the trimmings are sold as a lower grade. The trimmed sheets are sometimes passed between steel rollers, which reduce them to the thickness of paper; it then appears as a transparent ribbon, " shot " like watered silk. The ribbon is dried, and, if necessary, cut into strips.
The principal use of isinglass is for clarifying wines, beers and other liquids. This property is the more remarkable since it is not possessed by ordinary gelatin; it has been ascribed to its fibrous structure, which forms, as it were, a fine network in the liquid in which it is disseminated, and thereby mechanically carries down all the minute particles which occasion the turbidity. The cheaper varieties are more commonly used; many brewers prefer the Penang product; Russian leaf, however, is used by some Scottish brewers; and Russian long staple is used in the Worcestershire cider industry. Of secondary importance is its use for culinary and confectionery purposes, for example, in making jellies, stiffening jams, &c. Here it is often replaced by the so-called " patent isinglass, " which is a very pure gelatin, and differs from natural isinglass by being useless for clarifying liquids. It has few other applications in the arts. Mixed with gum, it is employed to give a lustre to ribbons and silk; incorporated with water, Spanish liquorice 'and lamp black it forms an Indian ink; a solution, mixed with a little tincture of benzoin, brushed over sarsenet and allowed to dry, forms the well-known " court plaster." Another plaster is obtained by adding acetic acid and a little otto of roses to a solution of fine glue. It also has valuable agglutinating properties; by dissolving in two parts of pure alcohol it forms a diamond cement, the solution cooling to a white, opaque, hard solid; it also dissolves in strong acetic acid to form a powerful cement, which is especially useful for repairing glass, pottery and like substances.
ISIS (Egyptian Ese), the most famous of the Egyptian goddesses. She was of human form, in early times distinguished only by the hieroglyph of her name upon her head. Later she commonly wore the horns of a cow, and the cow was sacred to her; it is doubtful, however, whether she had any animal representation in early times, nor had she possession of any considerable locality until a late period, when Philae, Behbét and other large temples were dedicated to her worship. Yet she was of great importance in mythology, religion and magic, appearing constantly in the very ancient Pyramid texts as the devoted sister-wife of Osiris and mother of Horus. In the divine genealogies she is daughter of Keb and Nut (earth and sky). She was supreme in magical power, cunning and knowledge. A legend of the New Kingdom tells how she contrived to learn the all-powerful hidden name of Ré' which he had confided to no one. A snake which she had fashioned for the purpose stung the god, who sent for her as a last resort in his unendurable agony; whereupon she represented to him that nothing but his own mysterious name could overcome the venom of the snake. Much Egyptian magic turns on the healing or protection of Horus by Isis, and it is chiefly from magical texts that the myth of Isis and Osiris as given by Plutarch can be illustrated. The Metternich stela (XXXth Dynasty), the finest example of a class of prophylactic stelae generally known by the name of " Horus on the crocodiles, " is inscribed with a long text relating the adventures of Isis and Horus in the marshes of the Delta. With her sister Nephthys, Isis is frequently represented as watching the body of Osiris or mourning his death. Isis was identified with Demeter by Herodotus, and described as the goddess who was held to be the greatest by the Egyptians; he states that she and Osiris, unlike other deities, were worshipped throughout the land. The importance of Isis had increased greatly since the end of the New Kingdom. The great temple of Philae was begun under the XXXth Dynasty; that of Behbét seems to have been built by Ptolemy II. The cult of Isis spread into Greece with that of Serapis early in the 3rd century B.C. In Egypt itself Isea, or shrines of Isis, swarmed. At Coptos Isis became a leading divinity on a par with the early god Min. About 80 B.C. Sulla founded an Isiac college in Rome, but their altars within the city were overthrown by the consuls no less than four times in the decade from 58 to 48 B.C., and the worship of Isis at Rome continued to be limited or suppressed by a succession of enactments which were enforced until the reign of Caligula. The Isiac mysteries were a representation of the chief events in the myth of Isis and Osiris-the murder of Osiris, the lamentations of Isis and her wanderings, followed by the triumph of Horus over Seth and the resurrection of the slain god-accompanied by music and an exposition of the inner meaning- of the spectacle. These were traditional in ancient Egypt, and in their later development were no doubt affected by the Eleusinian mysteries of Demeter. They appealed powerfully to the imagination and the religious sense. The initiated went through rites of purification, and practised a degree of asceticism; but for many the festival was believed to be an occasion for dark orgies. Isis nursing the child Horus (Hats pokhrates) was a very common figure in the Deltaic period, and in these later days was still a favourite representation. The Isis temples discovered at Pompeii and in Rome show that ancient monuments as well as objects of small size were brought from Egypt to Italy for dedication to her worship, but the goddess absorbed the attributes of all female divinities; she was goddess of the earth and its fruits, of the Nile, of the sea, of the underworld, of love, healing and magic. From the time of Vespasian onwards the worship of Isis, always popular with some sections, had a great vogue throughout the western world, and is not without traces in Britain. It proved the most successful