IODINE, a non-metallic element originally obtained from kelp, but now found in South America in combination with sodium, used largely both free and in combination in medicine and surgery, in photography, and in making aniline dyes.

IODOFORM, a crystalline substance similar to chloroform in composition, only in it iodine takes the place of chlorine; it is used in surgery as an antiseptic.

IOLCUS, a town in Thessaly, the port from which the Argonauts sailed in quest of the Golden Fleece.

ION, in the Greek mythology son of Apollo by Creusa, and exposed by her in the cave where she bore him, but who was conveyed by the god to Delphi and educated by a priestess, and was afterwards owned by his mother, and became the ancestor of the Ionians, her husband, Xuthus, being kept throughout in the dark.

IONA, a fertile little island 11/2 m.  W. of Mull, where St. Columba landed from Ireland A.D. 563, and built a monastery which was for centuries the centre of ecclesiastical life and missionary enterprise among the Scots of Scotland and Ireland and the Angles of the N. of England.  It is 31/2 m. long and 11/2 broad.

IONIA, ancient name of the western districts of Asia Minor between the Hermus and the Maeander, with adjacent islands; was colonised by Greeks 1050 B.C., and its chief cities, including Miletus, Ephesus, Samos, Chios, and later Smyrna, formed the Ionian League; the Ionians were noted for wealth, art, and luxury; coming under Persian yoke in 557 B.C. they deserted to Greece 479 B.C., in the great war, and became again independent; from 387 B.C. they were again under Persia till Alexander the Great took them and merged their history in that of the surrounding peoples.

IONIAN ISLANDS (250), a chain of forty mountainous islands lying off the W. coast of Greece, the largest being Corfu (78), Santa Maura (25), Cephalonia (80), and Zante (44).  The climate is good, and there is much fertile soil in the valleys except in Cephalonia; corn, grapes, and currants are grown; sulphur and coal are found in Corfu; their history has been very chequered; after belonging at different times to Venice, France and Turkey, they were seized by Britain and constituted a dependency in 1815; never satisfied with British rule, they were a source of constant friction which Mr. Gladstone’s mission in 1858 was insufficient to allay, and were handed over to Greece in 1863.

IONIC ORDER, an order of Grecian architecture, characterised by the volute of its capital in the form of a ram’s horn, and in which the cornice is dentated, the shaft fluted, and the entablature plain or embellished.

IONIC SCHOOL, the name of the earliest of the schools of philosophy in Greece, the prominent members of which were natives of Ionia, one and all of whom traced the beginning or basis of things back to the action of some physical agent, such as water, air, fire, &c., and among whom are reckoned such men as Thales, Anaximander, Anaximenes, and Heraclitus.