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IDRIA, a mining town in Carniola, Austria, 25 m. W. of Laibach. Pop. (1900) 5772. It is situated in a narrow Alpine valley, on the river Idria, an affluent of the Isonzo, and owes its prosperity to the rich mines of quicksilver which were accidentally discovered in 1497. Since 1580 they have been under the management of the government. The mercurial ore lies in a bed of clay slate, and is found both mingled with schist and in the form of cinnabar. A special excellence of the ore is the greatness of the yield of pure metal compared with the amount of the refuse. As regards the quantity annually extracted, the mines of Idria rank second to those of Almaden in Spain, which are the richest in the world.

IDRIALIN, a mineral wax accompanying the mercury ore in Idria. According to Goldschmidt it can be extracted by means of xylol, amyl alcohol or turpentine; also without decomposition. by distillation in a current of hydrogen, or carbon dioxide. It is a white crystalline body, very difficultly fusible, boiling above 440° C. (824° F.), of the composition C40H28O. Its solution in glacial acetic acid, by oxidation with chromic acid, yielded a red powdery solid and a fatty acid fusing at 62° C., and exhibiting all the characters of a mixture of palmitic and stearic acids.

IDRISI, or Edrisi [Abu Abdallah Mahommed Ibn Mahommed Ibn Abdallah Ibn Idrisi, c. A.D. 1099-1154], Arabic geographer. Very little is known of his life. Having left Islamic lands and become the courtier and panegyrist of a Christian prince, though himself a descendant of the Prophet, he was probably regarded by strict Moslems as a scandal, whose name should not, if possible, be mentioned. His great-grandfather, Idrisi II., “ Biamrillah, ” a member of the great princely house which had reigned for a time as caliphs in north-west Africa, was prince of Malaga, and likewise laid claim to the supreme title (Commander of the Faithful). After his death in 1055, Malaga was seized by Granada (1057), and the Idrisi family then probably migrated to Ceuta, where a freedman of theirs held power. Here the geographer appears to have been born in A.H. 493 (A.D. 1099). He is said to have studied at Cordova, and this tradition is confirmed by his elaborate and enthusiastic description of that city in his geography. From this work we know that he had visited, at some period of his life before A.D. 1154, both Lisbon and the mines of Andalusia. He had also once resided near Morocco city, and once was at (Algerian) Constantine. More precisely, he tells us that in A.D. 1117~he went to see the cave of the Seven Sleepers at Ephesus; he probably travelled extensively in Asia Minor. From doubtful readings in his text some have inferred that he had seen part of the coasts of France and England. We do not know when Roger II. of Sicily (1101-1154) invited him to his court, but it must have been between X125 and 1150. Idrisi made for the Norman king a celestial sphere and a disk representing the known world of his dayboth in silver. These only absorbed one-third of the metal that had been given him for the work, but Roger bestowed on him the remaining two-thirds as a present, adding to this 100,000 pieces of money and the cargo of a richly-laden ship from Barcelona. Roger next enlisted Idrisi's services in the compilation of a fresh description of the “ inhabited' earth ” from observation, and not merely from books. The king and his geographer chose emissaries whom they sent out into various countries to observe, record and design; as they returned, ldrisi inserted in the new geography the information they brought. Thus was gradually completed (by the month of Shawwal, A.H. 548=mid-]anuary, A.D. 1154), the famous work, best known. from its patron and originator, as AJ Rojo/i, but whose fullest title seems to have been, The going out of a Curious Man to e.rpIoro the Regions of the Globe, its Provinces, Islands, Cities and I/ieir Dimensions ond Situation. This has been abbreviated to The Amusement of him who desires to traverse the Earth, or The Relaxation of o Curious Miizd. The title of Nubian Geography, based upon Sionita and Hezronita's misreading of a passage relating to Nubia and the Nile, is entirely unwarranted and misleading. The Rogerion 7'r<>oti.1e contains a full description of the world as far as it was known to the author. The “ inhabited earth ” is divided into seven “ climates, ” beginning at the equinoctial line, and extending northwards to the limit at which the earth was supposed to be rendered uninhabitable by cold. Each climate is then divided by perpendicular lines into eleven equal parts, beginning with the western coast of Africa and ending with the eastern coast of Asia. The whole world is thus formed into seventy-seven equal square compartments. The geographer begins with the first part of the first climate, including the westernmost part of the Sahara and a small (north-westerly) section of the Sudan (of which a vague knowledge had now been acquired by the M oslems of Barbary), and thence proceeds eastward through the different divisions of this climate till he finds its termination in the Sea of China. He then returns to the first part of the second climate, and so proceeds till he reaches the eleventh part of the seventh climate, which terminates in north-east Asia, as he conceives that continent. The inconveniences of the arrangement (ignoring all divisions, physical, political, linguistic or religious, which did not coincide with those of his “climates”) are obvious. Though Idrisi was in such close relations with one of the most civilized of Christian courts and states, we find few traces of his influence on European thought and knowledge. The chief exception is perhaps in the delineation of Africa in the world maps of Marino Sanuto (q.11.) and Pietro Vesconte. His account of the voyage of the Maghrurin or “ Deceived Men” of Lisbon in the Atlantic (a voyage on which they seem to have visited Madeira and one of the Canaries) may have had some effect in stimulating the later ocean enterprise of Christian mariners; but we have no direct evidence of this. Idrisi's Ptolemaic leanings give a distinctly retrograde character to certain parts of his work, such as east Africa and south Asia; and, in spite of the record of the Lisbon Wanderers, he fully shares the common Moslem dread of the black, viscous, stormy and wind-swept waters of the western ocean, whose limits no one knew, and over which thick and perpetual darkness brooded. At the same time his breadth of view, his clear recognition of scientific truths (such as the roundness of the world) and his wide knowledge and intelligent application of preceding work (such as that of Ptolemy, Masudi and Al Jayhani) must not be forgotten. He also preserves and embodies a considerable amount of private and special information-especially as to Scandinavia (in whose delineation he far surpasses his predecessors), portions of the African coast, the river Niger (whose name is perhaps first to be found, after Ptolemy's doubtful Nigeir, in Idrisi), portions of the African coast, Egypt, Syria, Italy, France, the Adriatic shore-lands, Germany and the Atlantic islands. No other Arabic work contains a larger assortment of valuable geographical facts; unfortunately the place-names are often illegible or hopelessly corrupted in the manuscripts. Idrisi's world-map, with all its shortcomings, is perhaps the best product of that strangely feeble thing-the Mahommedan cartography of the middle ages. Besides the Rojari, Idrisi wrote another work, largely geographical, cited by Abulfida as The Book of Kingdoms, but apparently entitled by its author The Gardens of Humanity and the Amusement of the Soul. This was composed for William the Bad (1154-1166), son and successor of Roger II., but is now lost. He likewise wrote, according to Ibn Said, on M edicaments, and composed verses, which are referred to by the Sicilian Mahommedan poet Ibn Bashrun.

Two manuscripts of Idrisi exist in the Bibliothéque Nationale, Paris, and other two in the Bodleian Library, Oxford. One of the English MSS., brought from Egypt by Greaves, i s illustrated by a map of the known world, and by thirty-three sectional maps (for eac part of the first three climates). The second manuscript, brought by Pococke from Syria, bears the date of A.H. 906, or A.D. 1500. It consists of gzoleaves. and is illustrated by one general and seventy seven particular maps, the latter consequently including all the parts of every climate. The general map was published by Dr Vincent in his Periplus of the Erythraean Sea. A copy of Idrisi's work in the Escorial was destroyed by the fire of 1671.

An- epitome of Idrisi's geography, in the original Arabic, was printed, with many errors, in I5Q2 at the l/ledicean press in Rome, from a MS. preserved in the Grand Ducal library at Florence (Dr geogropllio. 1/niz'f'rs1zli. Ilmtulus ('1lll'li. YShH1M.S' . .). Even the description of Mecca is here omitted. Pococke supplied it from