202 I O I D the imperial control over the election of bishops in Ger many came to be in practice much curtailed, partly by the tacitly changed relations between the empire and its feuda tories, partly by explicit concessions wrung at various times from individual emperors (Otto IV. in 1209, Frederick II. in 1213); but the principles of the concordat of Worms continued theoretically to regulate the tenure of bishoprics and abbacies until the dissolution of the empire in 1806. The question of investitures never assumed an aspect of first rate importance in France, partly because the bishoprics there partook less than in Germany of the nature of secular principalities, partly because at an early period in the dispute the sovereigns voluntarily yielded the leading claims of the church party. In England an arrangement was come to as early as 1105 between Pascal II. and Henry I., in virtue of which the king gave up the right to invest with staff and ring, but retained the right to nominate his bishops and to exact from them the oath of allegiance. A certain freedom of election, somewhat similar to that which still exists (but see BISHOP), was first conceded under Stephen, and confirmed by John in 1215. 10 is the heroine of a legend associated with the cultus of Hera, both in Argos and in Euboea. In Argos the great temple of Hera was situated on a hill called Euboea, on the road from Mycenae to the city of Argos ; while in Eubcea the legend was associated with the town of Argoura. The identity of names shows that the legend dates from a very ancient period of the worship ; and as, in accordance with the universal rule in such legends, lo is only a form of the goddess, ifc is highly probable that she represents an older stage of the cultus than the better known Hera. Her transformation into a cow is clearly a relic of the primitive time when the goddess was actually worshipped under the symbol of a cow, the fertile mother, united with the male deity in the tepos ya/xos which was annually celebrated at Argos (see HERA). Even in the simplest form in which we know it, the legend has been much transformed by poetic fancy. As a heroine united with the country from immemorial time, lo is called daughter of Inachus, the river of Argos and its oldest king, or of lasus, from whom comes the epithet "laa-ov "Apyos. As associated with the oldest worship of Hera, she is called the daughter of Peiras, who made the first image of the goddess out of a pear tree at Tiryns ; and lo Callithyia is, by a common device in such legends, the first priestess of the goddess. Zeus fell in love with her, and she was transformed into a white cow either by Zeus, to hide her from the rage of Hera, or by the jealous goddess herself. When lo and Hera had once been made into dis tinct personalities, such tales easily arose to explain the relation between them. Hera then insisted on getting this cow from Zeus, and set Argus Panoptes with his thousand eyes to watch her. lo is almost universally understood to be the moon, and Argus the star-studded nightly heaven. Argus tied the cow to the olive tree shown in the sacred grove on Mount Euboea, or according to the poets pastured her in the fertile meadows of Lerna or Nemea. Zeus now sends his messenger Hermes, who lulls Argos to sleep with his magic wand, and slays him with the same curved sword, harpe, with which afterwards Perseus, the light-hero, slew the Gorgon, the power of darkness. According to another account Argus, the darkness, is slain by a stone thrown by Hermes, i.e., by the rising sun, whose sudden appearance is frequently spoken of as the throwing of a stone (Kuhn, Entwickl. d. Mythol.). Maddened by a gadfly, lo wanders over many lands till at last she comes to Egypt, where she regains human form and becomes the mother of Epaphus. Opinions differ much as to the interpretation of this part of the tale. It is not probable that both Zeus and Hermes figured in the original legend ; and the end has certainly been adapted so as to bring Greece and Egypt into con nexion, and dates therefore from the time when intercourse between them became frequent and much influence was exerted by Egyptian religion on Greek thought, i.e., the 7th century B.C. How far Oriental influence had affected the cultus at the period to which the origin of the legend belongs is doubtful ; Preller compares the Phoenician conception of Astarte as a wandering cow. In later time Isis, who was conceived as horned (Herod, ii. 41), was connected with lo. The legend of lo was a favourite subject among Greek "painters, and many representations are preserved on vases and in wall paintings (see Overbeck, Kunstmyth. d. Zeus, 465). See the works quoted under HETCMES ; and against the explanation of lo as the moon see Flew in N. Jahrbb., 1870 and 1873. IODINE, thus named on account of the violet colour of its vapour (toetS^s, violet-coloured), one of the so-called halogen elements, has already been partially described (see CHEMISTRY, vol. v. pp. 490-498). Iodides occur in minute quantity in most mineral waters and in sea water. The ashes of many marine algte are rich in them ; and formerly iodine was chiefly extracted from kelp or varec, the ashes of sea-weed, by distilling the mother liquor remaining after the separation of the less soluble salts by crystallization with manganese dioxide and sulphuric acid. Of late years, however, large quan tities of iodine have been obtained from crude Chili saltpetre by a similar process, The chief use of iodine is in the preparation of methyl- iodide, a substance employed in the manufacture of certain of the so-called aniline dyes. In medicine it is frequently applied externally as an irritant. Potassium iodide is also an important medicinal agent ; and iodoform, CIII 3 , a substance prepared by acting on alcohol with iodine in presence of alkali, has latterly been introduced as an agent for external application in certain diseases. Several iodides, especially ammonium, cadmium, and potassium iodide, are largely employed in photography. Ilecent investigations have disclosed a number of most remarkable facts regarding the behaviour of iodine, and the allied elements bromine and chlorine, which merit a brief description here. Free chlorine, bromine, and iodine are respectively represented by the formulae C1 2 , Br 9 , and I 2 ; that is to say, their molecules are "diatomic," each consisting of two atoms (comp. vol. v. pp. 467-472). On the other hand, the molecules of which sulphur vapour at a temperature of about 500 C. consists are hexatomic, as expressed by the formula S c ; but on raising the tempera ture these molecules undergo simplification, so that at temperatures above 800 the vapour appears to consist entirely of diatomic molecules such as are indicated by the formula S 2 . It would seem that the halogens undergo a similar molecular simplification when heated. Having devised a method of extreme simplicity for the determination of vapour density, V. Meyer was led in the summer of 1879 to determine the density of a number of elementary bodies at much higher temperatures than had previously been employed, and among others chlorine was examined. He was then led (in conjunction with C. Meyer) to the discovery that at high temperatures this gas has a very much lower density than corresponds to the formula C1 2 (Bericlite der deutschen chemischen Gesellschaft zu Berlin, 1879, p. 1430; comp. ibid., 1880, p. 1172). Subsequently he extended his observations to bromine and iodine (ibid., 1880, p. 394), and with similar results. Meier and Crafts took up the subject with the object of verifying V. Meyer s statements (ibid., 1880, p. 851) ; they introduced several refinements in the method of operating, and determined the temperatures at which the experiments were made more accurately ; in the main, however, their observations with iodine were confirmatory of V. Meyer s. V. Meyer s original results, and those of Meier and Crafts,
