volume V, pressure P and temperature T (see CONDENSATION OF GASES). In

this equation a relates to molecular attraction; and it is not improbable that in isomeric molecules, containing in sum the same amount of the same atoms, those mutual attractions are approximately the same, whereas the chief difference lies in the value of b, that is, the volume occupied by the molecule itself. For what reason this volume may differ from case to case lies close at hand; in connexion with the notion of negative and positive atoms, like chlorine and hydrogen, experience tends to show that the former, as well as the latter, have a mutual repulsive power, but the former acts on the latter in the opposite sense; the necessary consequence is that, when those negative and positive groups are distributed in the molecule, its volume will be smaller than if the negative elements are heaped together. An example may prove this, but before quoting it, the question of determining b must be decided; this results immediately from the above quotation, b being the volume V at the absolute zero (T = 0); so the volume of isomers ought to be compared at the absolute zero. Since this has not been done we must adopt the approximate rule that the volume at absolute zero is proportional to that at the boiling-point. Now taking the isomers H3C.CCl3(M_v = 108) and ClH2.CHCl2(M_v = 103), we see the negative chlorine atoms heaped up in the left hand formula, but distributed in the second; the former therefore may be presumed to occupy a larger space, the molecular volume, that is, the volume in cubic centimetres occupied by the molecular weight in grams, actually being 108 in the former, and 103 in the latter case (compare CHEMISTRY: _Physical_). An analogous remark applies to the boiling-point of isomers. According to the above formula the critical temperature is given by 8aA/54b, and as the critical temperature is approximately proportional to the boiling-point, both being estimated on the absolute scale of temperature, we may conclude that the larger value of b corresponds to the lower boiling-point, and indeed the isomer corresponding to the left-hand formula boils at 74 deg., the other at 114 deg. Other physical properties might be considered; as a general rule they depend upon the distribution of negative and positive elements in the molecule.

_Reversible (dynamical) Isomerism._--Certain investigations on isomerism which have become especially prominent in recent times bear on the possibility of the mutual transformation of isomers. As soon as this reversibility is introduced, general laws related to thermodynamics are applicable (see CHEMICAL ACTION; ENERGETICS). These laws have the advantage of being applicable to the mutual transformations of isomers, whatever be the nature of the deeper origin, and so bring polymerism, metamerism and polymorphism together. As they are pursued furthest in the last case, this may be used as an example. The study of polymorphism has been especially pursued by Otto Lehmann, who proved that it is an almost general property; the variety of forms which a given substance may show is often great, ammonium nitrate, for instance, showing at least four of them before melting. The general rule which correlates this polymorphic change is that its direction changes at a given temperature. For example, sulphur is stable in the rhombic form till 95.4 deg., from then upwards it tends to change over into the prismatic form. The phenomenon absolutely corresponds to that of fusion and solidification, only that it generally takes place less quickly; consequently we may have prismatic sulphur at ordinary temperature for some time, as well as rhombic sulphur at 100 deg. This may be expressed in the chosen case by a symbol; "rhombic sulphur <--95.4 deg.--> prismatic sulphur," indicating that there is equilibrium at the so-called "transition-point," 95.4 deg., and opposite change below and above.

This comparison with fusion introduces a second notion, that of the "triple-point," this being in the melting-phenomenon the only temperature at which solid, liquid and vapour are in equilibrium, in other words, where three phases of one substance are co-existent. This temperature is somewhat different from the ordinary melting-point, the latter corresponding to atmospheric pressure, the former to the maximum vapour-pressure; and so we come to a third relation for polymorphism. Just as the melting-point changes with pressure, the transition-point also changes; even the same quantitative relation holds for both, as L. J. Reicher proved with sulphur: aT/aP = AvT/q, v being the change in volume which accompanies the change from rhombic to prismatic sulphur, and q the heat absorbed. Both formula and experiment proved that an increase of pressure of one atmosphere elevated the transition point for about 0.04 deg. The same laws apply to cases of more complicated nature, and one of them, which deserves to be pursued further, is the mutual transformation of cyanuric acid, C3H3N3O3, cyanic acid, CHNO, and cyamelide (CHNO)_x; the first corresponding to prismatic sulphur, stable at higher temperatures, the last to rhombic, the equilibrium-symbol being: cyamelide <--150 deg.--> cyanuric acid; the cyanic acid corresponds to sulphur vapour, being in equilibrium with either cyamelide or cyanuric acid at a maximum pressure, definite for each temperature.

A second law for these mutual transformations is that when they take place without loss of homogeneity, for example, in the liquid state, the definite transition point disappears and the change is gradual. This seems to be the case with molten sulphur, which, when heated, becomes dark-coloured and plastic; and also in the case of metals, which obtain or lose magnetic properties without loss of continuous structure. At the same time, however, the transition point sometimes reappears even in the liquid state; in such cases two layers are formed, as has been recently observed with sulphur, and by F. M. Jager in complicated organic compounds. Thus the introduction of heterogeneity, or the appearance of a new phase, demands the existence of a fixed temperature of transformation.

On the basis of the relation between physical phenomena and thermodynamical laws, properties of the polymorphous compounds may be predicted. The chief consideration here is that the stable form must have the lower vapour pressure, otherwise, by distillation, it would transform in opposite sense. From this it follows that the stable form must have the higher melting-point, since at the melting-point the vapour of the solid and of the liquid have the same pressure. Thus prismatic sulphur has a higher melting-point (120 deg.) than the rhombic form (116 deg.), and it is even possible to calculate the difference theoretically from the thermodynamic relations. A third consequence is that the stable form must have the smaller solubility: J. Meyer and J. N. Bronstedt found that at 25 deg., 10 c.c. of benzene dissolved 0.25 and 0.18 gr. of prismatic and rhombic sulphur respectively. It can be easily seen that this ratio, according to Henry's law, must correspond to that of vapour-pressures, and so be independent of the solvent; in fact, in alcohol the figures are 0.0066 and 0.0052. Recently Hermann Walther Nernst has been able to deduce the transition-point in the case of sulphur from the specific heat and the heat developed in the transition only. This best studied case shows that a number of mutual relations are to be found between the properties of two modifications when once the phenomenon of mutual transformation is accessible.

In ordinary isomers indications of mutual transformation often occur; and among these the predominant fact is that denoted as tautomerism or pseudomerism. It exhibits itself in the peculiar behaviour of some organic compounds containing the group --C.CO.C--, e.g. CH3CO.CHX.CO2C2H5, derivatives of acetoacetic ester. These compounds generally behave as ketones; but at the same time they may act as alcohols, i.e. as if containing the OH group; this leads to the formula H3C.C(OH):CX.CO2C2H5. In reality such tautomeric compounds are apparently a mixture of two isomers in equilibrium, and indeed in some cases both forms have been isolated; then one speaks of _desmotropy_ (Gr. [Greek: desmos], a bond or link, and [Greek: trope], a turn or change). Nevertheless, the relations obtained in reversible cases such as sulphur have not yet found application in the highly interesting cases of ordinary irreversible isomerism.

A further step in this direction has been effected by the introduction of reversibility into a non-reversible case by means of a catalytic agent. The substance investigated was acetaldehyde, C2H4O, in its relation to paraldehyde, a polymeric modification. The phenomena were first observed without mutual transformation, aldehyde melting at -118 deg., paraldehyde at 13 deg., the only mutual influence being a lowering of melting-point, with a minimum at -120 deg. in the eutectic point. When a catalytic agent, such as sulphurous acid, is added, which produces a mutual change, the whole behaviour is different; only one melting-point, viz. 7 deg., is observed for all mixtures; this has been called the "natural melting-point." It corresponds to one of the melting-points in the series without catalytic agents, viz. in that mixture which contains 88% of paraldehyde and 12% of acetaldehyde, which the catalytic agent leaves unaffected. Such an introduction of reversibility is also possible by allowing sufficient time to permit the transformation to be produced by itself. By R. Rothe and Alexander Smith's interesting observations on sulphur, results have been obtained which tend to prove that the melting-point, as well as the appearance of two layers in the liquid state, correspond to unstable conditions. (J. H. van't H.)

ISOTHERM (Gr. [Greek: isos], equal, and [Greek: therme], heat), a line upon a map connecting places where the temperature is the same at sea-level on the earth's surface. These isothermal lines will be found to vary from month to month over the two hemispheres, or over local areas, during summer and winter, and their position is modified by continental or oceanic conditions.

ISOXAZOLES, monazole chemical compounds corresponding to furfurane, in which the [-=]CH group adjacent to the oxygen atom is replaced by a nitrogen atom, and therefore they contain the ring system

HC = N | \ | O. | / HC = CH

They may be prepared by the elimination of water from the monoximes of [beta]-diketones, [beta]-ketone aldehydes or oxymethylene ketones (L. Claisen, _Ber._, 1891, 24, p. 3906), the general reaction proceeding according to the equation

R.CO.CH2.CO.R + H2N.OH = 2H2O + R.C = N | \ | O. | / HC = C--R

W. Dunstan and T. S. Dymond (_Jour. Chem. Soc._, 1891, 49, p. 410) have also prepared isoxazoles by the action of alkalis on nitroparaffins, but have not been able to obtain the parent substance. Those isoxazoles in which the carbon atom adjacent to nitrogen is substituted are stable compounds, but if this is not the case, rearrangement of the molecule takes place and nitriles are formed. The isoxazoles are feebly basic.

The _isoxazolones_ are the keto derivatives of the as yet unknown dihydroisoxazole, and are compounds of strongly acid nature, decomposing the carbonates of the alkaline earth metals and forming salts with metals and with ammonia. Their constitution is not yet definitely fixed and they may be regarded as derived from one of the three types

CH2--C HC--CO HC = C(OH) | \ || \ | \ | O; || O; | O. | / || / | / CH = N HC--NH HC = N---

By the action of nitrous acid on the oxime of o-aminobenzophenone as [alpha]-phenyl indoxazene,

C--C6H5 / \\ C6H4 N, \ / O

is obtained; this is a derivative of benzisoxazole.

ISRAEL (Hebrew for "God strives" or "rules"; see Gen. xxxii. 28; and the allusion in Hosea xii. 4), the national designation of the Jews. Israel was a name borne by their ancestor Jacob the father of the twelve tribes. For some centuries the term was applied to the northern kingdom, as distinct from Judah, although the feeling of national unity extended it so as to include both. It emphasizes more particularly the position of the Hebrews as a religious community, bound together by common aims and by their covenant-relation with the national God, Yahweh.

See further JACOB, HEBREW LANGUAGE, HEBREW RELIGION, JEWS: _History_ and _Palestine_.

ISRAELI, ISAAC BEN SOLOMON (9th-10th centuries), Jewish physician and philosopher. A contemporary of Seadiah (q.v.), he was born and passed his life in North Africa. He died c. 950. At Kairawan, Israeli was court physician; he wrote several medical works in Arabic, and these were afterwards translated into Latin. Similarly his philosophical writings were translated, but his chief renown was in the circle of Moslem authors.

ISRAELS, JOSEF (1824- ), Dutch painter, was born at Groningen, of Hebrew parents, on the 27th of January 1824. His father intended him to be a man of business, and it was only after a determined struggle that he was allowed to enter on an artistic career. However, the attempts he made under the guidance of two second-rate painters in his native town--Buys and van Wicheren--while still working under his father as a stockbroker's clerk, led to his being sent to Amsterdam, where he became a pupil of Jan Kruseman and attended the drawing class at the academy. He then spent two years in Paris, working in Picot's studio, and returned to Amsterdam. There he remained till 1870, when he moved to The Hague for good. Israels is justly regarded as one of the greatest of Dutch painters. He has often been compared to J. F. Millet. As artists, even more than as painters in the strict sense of the word, they both, in fact, saw in the life of the poor and humble a motive for expressing with peculiar intensity their wide human sympathy; but Millet was the poet of placid rural life, while in almost all Israels' pictures we find some piercing note of woe. Duranty said of them that "they were painted with gloom and suffering." He began with historical and dramatic subjects in the romantic style of the day. By chance, after an illness, he went to recruit his strength at the fishing-town of Zandvoort near Haarlem, and there he was struck by the daily tragedy of life. Thenceforth he was possessed by a new vein of artistic expression, sincerely realistic, full of emotion and pity. Among his more important subsequent works are "The Zandvoort Fisherman" (in the Amsterdam gallery), "The Silent House" (which gained a gold medal at the Brussels Salon, 1858) and "Village Poor" (a prize at Manchester). In 1862 he achieved great success in London with his "Shipwrecked," purchased by Mr Young, and "The Cradle," two pictures of which the _Athenaeum_ spoke as "the most touching pictures of the exhibition." We may also mention among his maturer works "The Widower" (in the Mesdag collection), "When we grow Old" and "Alone in the World" (Amsterdam gallery), "An Interior" (Dordrecht gallery), "A Frugal Meal" (Glasgow museum), "Toilers of the Sea," "A Speechless Dialogue," "Between the Fields and the Seashore," "The Bric-a-brac Seller" (which gained medals of honour at the great Paris Exhibition of 1900). "David Singing before Saul," one of his latest works, seems to hint at a return on the part of the venerable artist to the Rembrandtesque note of his youth. As a water-colour painter and etcher he produced a vast number of works, which, like his oil paintings, are full of deep feeling. They are generally treated in broad masses of light and shade, which give prominence to the principal subject without any neglect of detail.

See Jan Veth, _Mannen of Beteckenis: Jozef Israels_; Chesneau, _Peintres francais et etrangers_; Ph. Zilcken, _Peintres hollandais modernes_ (1893); Dumas, _Illustrated Biographies of Modern Artists_ (1882-1884); J. de Meester, in Max Rooses' _Dutch Painters of the Nineteenth Century_ (1898); Jozef Israels, _Spain: the Story of a Journey_ (1900).

ISSACHAR (a Hebrew name meaning apparently "there is a hire," or "reward"), Jacob's ninth "son," his fifth by Leah; also the name of a tribe of Israel. Slightly differing explanations of the reference in the name are given in Gen. xxx. 16 (J) and v. 18 (E).[1] The territory of the tribe (Joshua xix. 17-23) lay to the south of that allotted to Zebulun, Naphtali, Asher and Dan, and included the whole of the great plain of Esdraelon, and the hills to the east of it, the boundary in that direction extending from Tabor to the Jordan, apparently along the deep gorge of Wadi el Bireh. In the rich territory of Issachar, traversed by the great commercial highway from the Mediterranean and Egypt to Bethshean and the Jordan, were several important towns which remained in the hands of the Canaanites for some time (Judges i. 27), separating the tribe from Manasseh. Although Issachar is mentioned as having taken some part in the war of freedom under Deborah (Judges v. 15), it is impossible to misunderstand the reference to its tributary condition in the blessing of Jacob (Gen. xlix. 14 seq.), or the fact that the name of this tribe is omitted from the list given in Judges i. of those who bestirred themselves against the earlier inhabitants of the country. In the "blessing upon Zebulun and Issachar" in Deut. xxxiii. 18 seq., reference is made to its agricultural life in terms suggesting that along with its younger, but more successful "brother," it was the guardian of a sacred mountain (Carmel, Tabor?) visited periodically for sacrificial feasts.

FOOTNOTE:

[1] On the origin of the name, see the article by H. W. Hogg, _Ency. Bib._ col. 2290; E. Meyer, _Israeliten_, p. 536 seq.

ISSEDONES, an ancient people of Central Asia at the end of the trade route leading north-east from Scythia (q.v.), described by Herodotus (iv. 26). The position of their country is fixed as the Tarym basin by the more precise indications of Ptolemy, who tells how a Syrian merchant penetrated as far as Issedon. They had their wives in common and were accustomed to slay the old people, eat their flesh and make cups of their skulls. Such usages survived among Tibetan tribes and make it likely that the Issedones were of Tibetan race. Some of the Issedones seem to have invaded the country of the Massagetae to the west, and similar customs are assigned to a section of these. (E. H. M.)

ISSERLEIN, ISRAEL (d. 1460), German Talmudist. His fame attracted many students to Neustadt, and his profound learning did much to revive the study of the original Rabbinic authorities. After the publication of the Code of Joseph Qaro (q.v.) the decisions of Isserlein in legal matters were added in notes to that code by Moses Isserles. His chief works were _Terumath ha-Deshen_ (354 decisions) and _Peasqim u-kethahim_ (267 decisions) largely on points of the marriage law.

ISSERLES, MOSES BEN ISRAEL (c. 1520-1572), known as REMA, was born at Cracow and died there in 1572. He wrote commentaries on the _Zohar_, the "Bible of the Kabbalists," but is best known as the critic and expander of the _Shulhan Aruch_ of Joseph Qaro (Caro)(q.v.). His chief halakhic (legal) works were _Darke Moshe_ and _Mappah_. Qaro, a Sephardic (Spanish) Jew, in his Code neglected Ashkenazic (German) customs. These deficiencies Isserles supplied, and the notes of Rema are now included in all editions of Qaro's Code.

ISSOIRE, a town of central France, capital of an arrondissement in the department of Puy-de-Dome, on the Couze, near its junction with the Allier, 22 m. S.S.E. of Clermont-Ferrand on the Paris-Lyon-Mediterranee railway to Nimes. Pop. (1906) 5274. Issoire is situated in the fertile plain of Limagne. The streets in the older part of the town are narrow and crooked, but in the newer part there are several fine tree-shaded promenades, while a handsome boulevard encircles the town. The church of St Paul or St Austremoine built on the site of an older chapel raised over the tomb of St Austremoine (Stremonius) affords an excellent specimen of the Romanesque architecture of Auvergne. Issoire is the seat of a sub-prefect; its public institutions include tribunals of first instance and commerce and a communal college. Brewing, wool-carding and the manufacture of passementerie, candles, straw hats and woollen goods are carried on. There is trade in lentils and other agricultural products, in fruit and in wine.

Issoire (_Iciodurum_) is said to have been founded by the Arverni, and in Roman times rose to some reputation for its schools. In the 5th century the Christian community established there by Stremonius in the 3rd century was overthrown by the fury of the Vandals. During the religious wars of the Reformation, Issoire suffered very severely. Merle, the leader of the Protestants, captured the town in 1574, and treated the inhabitants with great cruelty. The Roman Catholics retook it in 1577, and the ferocity of their retaliation may be inferred from the inscription "_Ici fut Issoire_" carved on a pillar which was raised on the site of the town. In the contest between the Leaguers and Henry IV., Issoire sustained further sieges, and never wholly regained its early prosperity.

ISSOUDUN, a town of central France, capital of an arrondissement in the department of Indre, on the right bank of the Theols, 17 m. N.E. of Chateauroux by rail. Pop. (1906) 10,566. Among the interesting buildings are the church of St Cyr, combining various architectural styles, with a fine porch and window, and the chapel of the Hotel Dieu of the early 16th century. Of the fortifications with which the town was formerly surrounded, a town-gate of the 16th century and the White Tower, a lofty cylindrical building of the reign of Philip Augustus, survive. Issoudun is the seat of a sub-prefecture, and has tribunals of first instance and of commerce, a chamber of arts and manufactures and a communal college. The industries, of which the most important is leather-dressing, also include malting and brewing and the manufacture of bristles for brushes and parchment. Trade is in grain, live-stock, leather and wine.

Issoudun, in Latin _Exoldunum_ or _Uxellodunum_, existed in and before Roman times. In 1195 it was stoutly and successfully defended by the partizans of Richard Coeur-de-Lion against Philip Augustus, king of France. It has suffered severely from fires. A very destructive one in 1651 was the result of an attack on the town in the war of Fronde; Louis XIV. rewarded its fidelity to him during that struggle by the grant of several privileges.

ISSYK-KUL, also called TUZ-KUL, and by the Mongols _Temurtu-nor_, a lake of Central Asia, lying in a deep basin (5400 ft. above sea-level), between the Kunghei Ala-tau and the Terskei Ala-tau, westward continuations of the Tian-shan mountains, and extending from 76 deg. 10' to 78 deg. 20' E. The length from W.S.W. to E.N.E. is 115 m. and the breadth 38 m., the area being estimated at 2230 sq. m. The name is Kirghiz for "warm lake," and, like the Chinese synonym She-hai, has reference to the fact that the lake is never entirely frozen over. On the south the Terskei Ala-tau do not come down so close to the shore as the mountains on the north, but leave a strip 5 to 13 m. broad. The margins of the lake are overgrown with reeds. The water is brackish. Fish are remarkably abundant, the principal species being carp.

It was by the route beside this lake that the tribes (e.g. Yue-chi) driven from China by the Huns found their way into the Aralo-Caspian basin in the end of the 2nd century. The Ussuns or Uzuns settled on the lake and built the town of Chi-gu, which still existed in the 5th century. It is to Hsuan-tsang, the Chinese Buddhist pilgrim, that we are indebted for the first account of Issyk-kul based on personal observation. In the beginning of the 14th century Nestorian Christians reached the lake and founded a monastery on the northern shore, indicated on the Catalan map of 1374. It was not till 1856 that the Russians made acquaintance with the district.

ISTAHBANAT, a town and district of Persia in the province of Fars. The district, which is very fertile, extends for nearly 50 m. east and west along the southern shore of the Bakhtegan lake and produces much grain, cotton, good tobacco and excellent fruit, particularly pomegranates and grapes, walnuts and figs. The town is situated in the midst of a plain 12 m. from the eastern corner of the lake and about 100 m. S.E. of Shiraz, and has a population of about 10,000. It occupies the site of the ancient city of Ij, the capital of the old province of Shabankareh, which was captured and partly destroyed by Mubariz ed-din, the founder of the Muzaffarid dynasty, in 1355. When rebuilt it became known by its present name. Of the old period a ruined mosque and two colleges remain; other mosques and colleges are of recent construction. At the entrance of the town stands a noble chinar (oriental plane), measuring 45 ft. in circumference at 2 ft. from the ground.

ISTHMUS (Gr. [Greek: isthmos], neck), a narrow neck of land connecting two larger portions of land that are otherwise separated by the sea.

ISTRIA (Ger. _Istrien_), a margraviate and crownland of Austria, bounded N. by the Triestine territory, Gorz and Gradisca, and Carniola, E. by Croatia and S. and W. by the Adriatic; area 1908 sq. m. It comprises the peninsula of the same name (area 1545 sq. m.), which stretches into the Adriatic Sea between the Gulf of Trieste and the Gulf of Quarnero, and the islands of Veglia, Cherso, Lussino and others. The coast line of Istria extends for 267 m., including Trieste, and presents many good bays and harbours. Besides the great Gulf of Trieste, the coast is indented on the W. by the bays of Muggia, Capodistria, Pirano, Porto Quieto and Pola, and on the E. by those of Medolino, Arsa, Fianona and Volosca. A great portion of Istria belongs to the Karst region, and is occupied by the so-called Istrian plateau, flanked on the north and east by high mountains, which attain in the Monte Maggiore an altitude of 4573 ft. In the south and west the surface gradually slopes down in undulating terraces towards the Adriatic. The Quieto in the west and the Arsa in the east, neither navigable, are the principal streams. The climate of Istria, although it varies with the varieties of surface, is on the whole warm and dry. The coasts are exposed to the prevailing winds, namely the _Sirocco_ from the south-south-east, and the _Bora_ from the north-east. Of the total area 33.21% is occupied by forests, 32.09% by pastures, 11.2% by arable land, 9.5% by vineyards, 7.21% by meadows and 3.26% by gardens. The principal agricultural products are wheat, maize, rye, oats and fruit, namely olives, figs and melons. Viticulture is well developed, and the best sorts of wine are produced near Capodistria, Muggia, Isola, Parenzo and Dignano, while well-known red wines are made near Refosco and Terrano. The oil of Istria was already famous in Roman times. Cattle-breeding is another great source of revenue, and the exploitation of the forests gives beech and oak timber (good for shipbuilding), gall-nuts, oak-bark and cork. Fishing, the recovery of salt from the sea-water, and shipbuilding constitute the other principal occupations of the population. Istria had in 1900 a population of 344,173, equivalent to 180 inhabitants per square mile. Two-thirds of the population were Slavs and the remainder Italians, while nearly the whole of the inhabitants (99.6%) were Roman Catholics, under the ecclesiastical jurisdiction of three bishops. The local Diet, which meets at Parenzo, and of which the three bishops are members _ex-officio_, is composed of 33 members, and Istria sends 5 deputies to the Reichsrat at Vienna. For administrative purposes the province is divided into 6 districts and an autonomous municipality, Rovigno (pop. 10,205). Other important places are Pola (45,052), Capodistria (10,711), Pinguente (15,827), Albona (10,968), Isola (7500), Parenzo (9962), Dignano (9684), Castua (17,988), Pirano (13,339) and Mitterburg (16,056).

The modern Istria occupies the same position as the ancient Istria or Histria, known to the Romans as the abode of a fierce tribe of Illyrian pirates. It owed its name to an old belief that the Danube (Ister, in Greek) discharged some of its water by an arm entering the Adriatic in that region. The Istrians, protected by the difficult navigation of their rocky coasts, were only subdued by the Romans in 177 B.C. after two wars. Under Augustus the greater part of the peninsula was added to Italy, and, when the seat of empire was removed to Ravenna, Istria reaped many benefits from the proximity of the capital. After the fall of the Western empire it was pillaged by the Longobardi and the Goths; it was annexed to the Frankish kingdom by Pippin in 789; and about the middle of the 10th century it fell into the hands of the dukes of Carinthia. Fortune after that, however, led it successively through the hands of the dukes of Meran, the duke of Bavaria and the patriarch of Aquileia, to the republic of Venice. Under this rule it remained till the peace of Campo Formio in 1797, when Austria acquired it, and added it to the north-eastern part which had fallen to her share so early as 1374. By the peace of Pressburg, Austria was in 1805 compelled to cede Istria to France, and the department of Istria was formed; but in 1813 Austria again seized it, and has retained it ever since.

See T. G. Jackson, _Dalmatia, the Quarnero and Istria_ (Oxford, 1887).

ISYLLUS, a Greek poet, whose name was rediscovered in the course of excavations on the site of the temple of Asclepius at Epidaurus. An inscription was found engraved on stone, consisting of 72 lines of verse (trochaic tetrameters, hexameters, ionics), mainly in the Doric dialect. It is preceded by two lines of prose stating that the author was Isyllus, an Epidaurian, and that it was dedicated to Asclepius and Apollo of Malea. It contains a few political remarks, showing general sympathy with an aristocratic form of government; a self-congratulatory notice of the resolution, passed at the poet's instigation, to arrange a solemn procession in honour of the two gods; a paean (no doubt for use in the procession), chiefly occupied with the genealogical relations of Apollo and Asclepius; a poem of thanks for the assistance rendered to Sparta by Asclepius against Philip, when he led an army against Sparta to put down the monarchy. The offer of assistance was made by the god himself to the youthful poet, who had entered the Asclepieum to pray for recovery from illness, and communicated the good news to the Spartans. The Philip referred to is identified with (a) Philip II. of Macedon, who invaded Peloponnesus after the battle of Chaeronea in 338, or (b) with Philip III., who undertook a similar campaign in 218.

Wilamowitz-Mollendorff, who characterizes Isyllus as a "poetaster without talent and a farcical politician," has written an elaborate treatise on him (Kiessling and Mollendorff, _Philosophische Untersuchungen_, Heft 9, 1886), containing the text with notes, and essays on the political condition of Peloponnesus and the cult of Asclepius. The inscription was first edited by P. Kavvadias (1885), and by J. F. Baunack in _Studien auf dem Gebiete der griechischen und der arischen Sprachen_ (1886).

ITACOLUMITE, the name given to a variety of porous yellow sandstone or quartzose schist, which occurs at Itacolumi, in the southern portion of Minas Geraes, Brazil. This rock is of interest for two reasons; it is believed to be the source of the diamonds which are found in great numbers in the district, and it is the best and most widely known example of a flexible sandstone. Itacolumite is yellow or pale-brown, and splits readily into thin flat slabs. It is a member of a metamorphic series, being accompanied by clay-slate, mica schist, hornblende schist and various types of ferriferous schists. In many places itacolumite is really a coarse grit or fine conglomerate. Other quartzites occur in the district, and there is some doubt whether the diamantiferous sandstones are always itacolumites and also as to the exact manner in which the presence of diamond in these rocks is to be accounted for. Some authorities hold that the diamond has been formed in certain quartz veins which traverse the itacolumite. It is clear, however, that the diamonds are found only in those streams which contain the detritus of this rock.

On the split faces of the slabs, scales of greenish mica are visible, but in other respects the rock seems to be remarkably pure. If a piece which is a foot or two long and half an inch thick be supported at its ends it will gradually bend by its own weight. If it then be turned over it will straighten and bend in the opposite direction. Flakes a millimetre or two thick can be bent between the fingers and are said to give out a creaking sound. It should be noted that specimens showing this property form only a small part of the whole mass of the rock. Flexible rocks have also been reported and described from North and South Carolina, Georgia, Delhi, and from the north of England (Durham). They are mostly sandstones or quartzites, but the Durham rock is a variety of the magnesian limestone of that district.

Some discussion has taken place regarding the cause of the flexibility. At one time it was ascribed to the presence of thin scales of mica which were believed to permit a certain amount of motion between adjacent grains of quartz. More probably, however it is due to the porous character of the rock together with the interlocking junctions between the sand grains. The porosity allows interstitial movement, while the hinge-like joints by which the particles are connected hold them together in spite of the displacement. These features are dependent to some extent on weathering, as the rocks contain perishable constituents which are removed and leave open cavities in their place, while at the same time additional silica may have been deposited on the quartz grains fitting their irregular surfaces more perfectly together. Most of the known flexible rocks are also fine-grained; in some cases they are said to lose their flexibility after being dried for some time, probably because of the hardening of some interstitial substance, but many specimens kept in a dry atmosphere for years retain this property in a high degree. (J. S. F.)

ITAGAKI, TAISUKE, COUNT (1837- ), Japanese statesman, was born in Tosa in 1837. He distinguished himself originally as one of the soldier politicians who contributed so much to the overthrow of feudalism and the restoration of the administrative power to the throne. After taking a prominent part in subduing the resistance offered by a section of the _shogun's_ feudatories to those changes, he received cabinet rank in the newly organized system. But in 1873 he resigned his portfolio as a protest against the ministry's resolve to refrain from warlike action against Korea. This incident inspired Itagaki with an apprehension that the country was about to pass under the yoke of a bureaucratic government. He became thenceforth a warm advocate of constitutional systems, though at the outset he does not seem to have contemplated anything like a popular assembly in the English sense of the term, his ideas being limited to the enfranchisement of the _samurai_ class. Failing to obtain currency for his radical propaganda, he retired to his native province, and there established a school (the _Risshi-sha_) for teaching the principles of government by the people, thus earning for himself the epithet of "the Rousseau of Japan." His example found imitators. Not only did pupils flock to Tosa from many quarters, attracted alike by the novelty of Itagaki's doctrines, by his eloquence and by his transparent sincerity, but also similar schools sprang up among the former vassals of other fiefs, who saw themselves excluded from the government. In 1875 no less than seven of these schools sent deputies to hold a convention in Osaka, and for a moment an appeal to force seemed possible. But the statesmen in power were not less favourable to constitutional institutions than the members of the _Aikoku Ko-to_ (public party of patriots), as Itagaki and his followers called themselves. A conference attended by Kido, Okubo, Inouye, Ito, Itagaki and others entered into an agreement by which they pledged themselves to the principle of a constitutional monarchy and a legislative assembly. Itagaki now accepted office once more. Finding, however, that his colleagues in the administration favoured a much more leisurely rate of progress than he himself advocated, he once more retired into private life (1876) and renewed his liberal propagandism. It is in the nature of such movements to develop violent phases, and the leaders of the _Aikoku-sha_ (patriotic association), as the agitators now called themselves, not infrequently showed disregard for the preservation of peace and order. Itagaki made the mistake of memorializing the government at the moment when its very existence was imperilled by the Satsuma rebellion (1877), and this evident disposition to take advantage of a great public peril went far to alienate the sympathies of the cabinet. Recourse was had to legislation in restraint of free speech and public meeting. But repression served only to provoke opposition. Throughout 1879 and 1880 Itagaki's followers evinced no little skill in employing the weapons of local association, public meetings and platform tours, and in November 1881 the first genuine political party was formed in Japan under the name of _Jiyu-to_, with Itagaki for declared leader. A year later the emperor announced that a parliamentary system should be inaugurated in 1891, and Itagaki's task might be said to have been accomplished. Thenceforth he devoted himself to consolidating his party. In the spring of 1882, he was stabbed by a fanatic during the reception given in the public park at Gifu. The words he addressed to his would-be assassin were: "Itagaki may perish, but liberty will survive." Once afterwards (1898) he held office as minister of home affairs, and in 1900 he stepped down from the leadership of the _Jiyu-to_ in order that the latter might form the nucleus of the _Seiyu-kai_ organized by Count Ito. Itagaki was raised to the nobility with the title of "count" in 1887. From the year 1900 he retired into private life, devoting himself to the solution of socialistic problems. His countrymen justly ascribe to him the fame of having been the first to organize and lead a political party in Japan.

ITALIAN LANGUAGE.[1] The Italian language is the language of culture in the whole of the present kingdom of Italy, in some parts of Switzerland (the canton of Ticino and part of the Grisons), in some parts of the Austrian territory (the districts of Trent and Gorz, Istria along with Trieste, and the Dalmatian coast), and in the islands of Corsica[2] and Malta. In the Ionian Islands, likewise, in the maritime cities of the Levant, in Egypt, and more particularly in Tunis, this literary language is extensively maintained through the numerous Italian colonies and the ancient traditions of trade.

The Italian language has its native seat and living source in Middle Italy, or more precisely Tuscany and indeed Florence. For real linguistic unity is far from existing in Italy; in some respects the variety is less, in others more observable than in other countries which equally boast a political and literary unity. Thus, for example, Italy affords no linguistic contrast so violent as that presented by Great Britain with its English dialects alongside of the Celtic dialects of Ireland, Scotland and Wales, or by France with the French dialects alongside of the Celtic dialects of Brittany, not to speak of the Basque of the Pyrenees and other heterogeneous elements. The presence of not a few Slavs stretching into the district of Udine (Friuli), of Albanian, Greek and Slav settlers in the southern provinces, with the Catalans of Alghero (Sardinia, v. _Arch. glott._ ix. 261 et seq.), a few Germans at Monte Rosa and in some corners of Venetia, and a remnant or two of other comparatively modern immigrations is not sufficient to produce any such strong contrast in the conditions of the national speech. But, on the other hand, the Neo-Latin dialects which live on side by side in Italy differ from each other much more markedly than, for example, the English dialects or the Spanish; and it must be added that, in Upper Italy especially, the familiar use of the dialects is tenaciously retained even by the most cultivated classes of the population.

In the present rapid sketch of the forms of speech which occur in modern Italy, before considering the Tuscan or Italian _par excellence_, the language which has come to be the noble organ of modern national culture, it will be convenient to discuss (A) dialects connected in a greater or less degree with Neo-Latin systems that are not peculiar to Italy;[3] (B) dialects which are detached from the true and proper Italian system, but form no integral part of any foreign Neo-Latin system; and (C) dialects which diverge more or less from the true Italian and Tuscan type, but which at the same time can be conjoined with the Tuscan as forming part of a special system of Neo-Latin dialects.

A. _Dialects which depend in a greater or less degree on Neo-Latin systems not peculiar to Italy._

1. _Franco-Provencal and Provencal Dialects._--(a) _Franco-Provencal_ (see Ascoli, _Arch. glott._ iii. 61-120; Suchier, in _Grundriss der romanischen Philologie_, 2nd ed., i. 755, &c.; Nigra, _Arch. glott._ iii. 1 sqq.; Salvioni, _Rendic. istit. lomb._, s. ii. vol. xxxvii. 1043 sqq.; Cerlogne, _Dictionnaire du patois valdotain_ (Aosta, 1907). These occupy at the present time very limited areas at the extreme north-west of the kingdom of Italy. The system stretches from the borders of Savoy and Valais into the upper basin of the Dora Baltea and into the head-valleys of the Orco, of the northern Stura, and of the Dora Riparia. As this portion is cut off by the Alps from the rest of the system, the type is badly preserved; in the valleys of the Stura and the Dora Riparia, indeed, it is passing away and everywhere yielding to the Piedmontese. The most salient characteristic of the Franco-Provencal is the phonetic phenomenon by which the Latin _a_, whether as an accented or as an unaccented final, is reduced to a thin vowel (_e_, _i_) when it follows a sound which is or has been palatal, but on the contrary is kept intact when it follows a sound of another sort. The following are examples from the Italian side of these Alps: AOSTA: _travalji_, Fr. travailler; _zarzi_, Fr. charger; _enteruzi_, Fr. interroger; _zevra_, Fr. chevre; _zir_, Fr. cher; _gljace_, Fr. glace; _vazze_, Fr. vache; alongside of _sa_, Fr. sel; _man_, Fr. main; _epousa_, Fr. epouse; _erba_, Fr. herbe. VAL. SOANA: _taljer_, Fr. tailler; _coci-sse_, Fr. se coucher; _cin_, Fr. chien; _civra_, Fr. chevre; _vacci_, Fr. vache; _mangi_, Fr. manche; alongside of _alar_, Fr. aller; _porta_, Fr. porte; _amara_, Fr. amere; _neva_, Fr. neuve. CHIAMORIO (Val di Lanzo): _la spranssi dla vendeta_, sperantia de illa vindicta. VIU: _pansci_, pancia. USSEGLIO: _la muragli_, muraille. A morphological characteristic is the preservation of that paradigm which is legitimately traced back to the Latin pluperfect indicative, although possibly it may arise from a fusion of this pluperfect with the imperfect subjunctive (amaram, amarem, alongside of habueram, haberem), having in Franco-Provencal as well as in Provencal and in the continental Italian dialects in which it will be met with further on (C. 3, b; cf. B. 2) the function of the conditional. VAL SOANA: _portaro_, _portare_, _portaret_; _portaront_; AOSTA: _avre_ = Prov. _agra_, haberet (see _Arch._ iii. 31 _n_). The final _t_ in the third persons of this paradigm in the Val Soana dialect is, or was, constant in the whole conjugation, and becomes in its turn a particular characteristic in this section of the Franco-Provencal. VAL SOANA: _eret_, Lat. erat; _sejt_, sit; _portet_, _portavet_; _portont_, _portavont_; CHIAMORIO: _jeret_, erat; _ant dit_, habent dictum; _ejssount fet_, habuissent factum; VIU: _che s'minget_, Ital. che si mangi: GRAVERE (Val di Susa): _at pensa_, ha pensato; _avat_, habebat; GIAGLIONE (sources of the Dora Riparia); _maciavont_, mangiavano.--From the valleys, where, as has just been said, the type is disappearing, a few examples of what is still genuine Franco-Provencal may be subjoined: _Civreri_ (the name of a mountain between the Stura and the Dora Riparia), which, according to the regular course of evolution, presupposes a Latin _Capraria_ (cf. _maneri_, maniera, even in the Chiamorio dialect); _carasti_ (_ciarasti_), carestia, in the Viu dialect; and _cinta_, cantare, in that of Usseglio. From CHIAMORIO, _li tens_, i tempi, and _chejches birbes_, alcune (qualche) birbe, are worthy of mention on account of the final _s_. [In this connexion should also be mentioned the Franco-Provencal colonies of Transalpine origin, Faeto and Celle, in Apulia (_v._ Morosi, _Archivio glottologico_, xii. 33-75), the linguistic relations of which are clearly shown by such examples as _talij_, Ital. tagliare; _banij_, Ital. bagnare; side by side with _canta_, Ital. cantare; _lua_, Ital. levare.]

(b) _Provencal_ (see _La Lettura_ i. 716-717, _Romanische Forschungen_ xxiii. 525-539).--Farther south, but still in the same western extremity of Piedmont, phenomena continuous with those of the Maritime Alps supply the means of passing from the Franco-Provencal to the Provencal proper, precisely as the same transition takes place beyond the Cottian Alps in Dauphine almost in the same latitude. On the Italian side of the Cottian and the Maritime Alps the Franco-Provencal and the Provencal are connected with each other by the continuity of the phenomenon _c_ (a pure explosive) from the Latin _c_ before _a_. At OULX (sources of the Dora Riparia), which seems, however, to have a rather mixed dialect, there also occurs the important Franco-Provencal phenomenon of the surd interdental (English _th_ in _thief_) instead of the surd sibilant (for example _ithi_ = Fr. ici). At the same time _agu_ = avuto, takes us to the Provencal. [If, in addition to the Provencal characteristic of which _agu_ is an example, we consider those characteristics also Provencal, such as the _o_ for _a_ final unaccented, the preservation of the Latin diphthong _au_, _p_ between vowels preserved as _b_, we shall find that they occur, together or separately, in all the Alpine varieties of Piedmont, from the upper valleys of the Dora Riparia and Clusone to the Colle di Tenda. Thus at FENESTRELLE (upper valley of the Clusone): _agu_, _vengu_, Ital. venuto; _pauc_, Lat. _paucu_, Ital. poco; _ariba_ (Lat. _ripa)_, Ital. arrivare; _truba_, Ital. trovare; _ciabrin_, Ital. capretto; at OULX (source of the Dora Riparia): _agu_, _vengu_; _uno gran famino e venuo_, Ital. una gran fame e venuta; at GIAGLIONE: _auvou_, Ital. odo (Lat. _audio_); _arriba_, _resebu_, Ital. ricevuto (Lat. _recipere_); at ONCINO (source of the Po): _agu_, _vengu_; _ero en campagno_, Ital. "era in campagna"; _donavo_, Ital. dava; _paure_, Lat. _pauper_, Ital. povero; _truba_, _ciabri_; at SANPEYRE (valley of the Varaita): _agu_, _volgu_, Ital. voluto; _pressioso_, Ital. preziosa; _fasio_, Ital. faceva; _trobar_; at ACCEGLIO (valley of the Macra): _venghess_, Ital. venisse; _virro_, Ital. ghiera; _chesto allegrio_, Ital. questa allegria; _ero_, Ital. era; _troba_; at CASTELMAGNO (valley of the Grana): _gu_, _vengu_; _rabbio_, Ital. rabbia; _trubar_; at VINADIO (valley of the southern Stura); _agu_, _beigu_, Ital. bevuto; _cadeno_, Ital. catena; _manggo_, Ital. manica; _canto_, Ital. canta; _pau_, _auvi_, Ital. udito; _sabe_, Ital. sapete; _trobar_; at VALDIERI and ROASCHIA (valley of the Gesso): _purgu_, Ital. potuto; _pjagu_, Ital. piaciuto; _corrogu_, Ital. corso; _pau_; _arriba_, _ciabri_; at LIMONE (Colle di Tenda): _agu_, _vengu_; _saber_, Ital. sapere; _aruba_, _trubava_. Provencal also, though of a character rather Transalpine (like that of Dauphine) than native, are the dialects of the Vaudois population above Pinerolo (_v._ Morosi, _Arch. glott._ xi. 309-416), and their colonies of Guardia in Calabria (ib.