Oxus - Encyclopedia

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OXUS, or AMU Darya, one of the great rivers of Central Asia. Prior to the meeting of the commissions appointed for the determination of the Russo-Afghan boundary in 1885, no very accurate geographical knowledge of the upper Oxus regions existed, and the course of the river itself was but roughly mapped. Russian explorers and natives of India trained for geographical reconnaissance, and employed in connexion with the great trigonometrical survey of India, had done so much towards clearing away the mists which enveloped the actual course of the river, that all the primary affluents were known, although their relative value was misunderstood, but the nature of the districts which bordered the river in Afghan Turkestan was so imperfectly mapped as to give rise to considerable political complication in framing the boundary agreement between Great Britain and Russia. From Lake Victoria (Sor-Kul) in the Pamirs, which was originally reckoned as the true source of the river, to Khamiab, on the edge of the Andkhui district of Afghan Turkestan, for a distance of about 680 m., the Oxus forms the boundary between Afghanistan and Russia. For another 550 m. below Khamiab it follows an open and sluggish course till it is lost in the Sea of Aral, being spanned at Charjui, 150 m. below Khamiab, by the wooden bridge which carries the Russian railway from Mer y to Samarkand. The level of Lake Victoria is 13,400 ft. above sea. At Khamiab the river is probably rather less than Soo ft.

For many years a lively geographical controversy circled about the sources of the Oxus, and the discussion derived some political, significance from the fact that the true source, wherever Sources. it might be found, was claimed as a point in the RussoAfghan boundary. The final survey of the Pamir region (wherein the heads of all the chief tributaries of the river lay hidden), by the Pamir boundary commission of 1895 established the following topographical facts in connexion with this question. The elevated mountain chain which is now called the Nicolas range, which divides the Great from the Little Pamir, is a region of vast glaciers and snow-fields, from which the lakes lying immediately north and south derive the greater part of their water-supply. On the north the principal glacial tributary of Lake Victoria forms, within the folds of the gigantic spurs of the Nicolas mountains, a series of smaller lakes, or lakelets, before joining the great lake itself. On the south a similar stream starting farther east, called Burgutai (denoting the position of a difficult and dangerous pass across the range) sweeps downwards towards Lake Chakmaktin, the lake of the Little Pamir, which is some 400 ft. lower than Victoria. But at the foot of the mountain this stream bifurcates in the swamps which lie to the west of Chakmaktin, and part of its waters find their way eastwards into the lake, and part flow away westwards into the Ab-i-Panja, which joins the Pamir river from Lake Victoria at Kala Panja. This at any rate is the action of the Burgutai stream during certain seasons of the year, so that the glaciers and snowfields of the Nicolas range may be regarded as the chief fountain-head of at least two of the upper tributaries of the Oxus, namely, the Aksu (or Murghab) and the Pamir river, and as contributing largely to a third, the Ab-i-Panja. Neither Lake Victoria nor Lake Chakmaktin derives any very large contributions from glacial sources other than those of the Nicolas range. It is possible that there may be warm springs on the bed of Lake Victoria, as such springs are of frequent occurrence in the Pamirs; but there is no indication of them in the Chakmaktin basin, and the latter lake must be regarded rather as an incident in the course of the Aksu - a widening of the river channel in the midst of this highlevel, glacier-formed valley - than as the fountain-head of the infant stream. There are indications that the bed of Lake Victoria, as well as that of Chakmaktin, is rapidly silting, and that the shores of the latter are gradually receding farther from the foot of the hills. The glacial origin of the Pamir valleys is everywhere apparent in their terrace formations and the erratic blocks and boulders that lie scattered about their surface. It is probable that the lakes themselves are evidence of (geologically) a comparatively recent deliverance from the thraldom of the ice covering, which has worn and rounded the lower ridges into the smooth outlines of undulating downs.

Another important source of the river (considered by Curzon to be the chief source) is to be found in the enormous glaciers which lie about the upper or main branch of the Ab-i-Panja (called the Ab-i-Wakhjir or Wakhan), which rises under the mountains enclosing the head of the Taghdumbash Pamirs. Although the superficial area of glacial ice from which the Ab-iWakhjir derives the greater part of its volume is not equal to that found on the Nicolas range, it is quite impossible to frame any estimate of comparative depth or bulk, or to separate the volume of its contributions at any time from those which, combined, derive their origin from the Nicolas range. If the Aksu (or Murghab) and the Pamir river from Lake Victoria are to be considered in the light of independent tributaries, it is probable that the Ab-i-Panja contributes as large a volume of glacial flood to the Oxus as either of them.

From the point where the rivers of the Great and Little Pamirs join their forces at Kala Panja to Ishkashim, at the elbow of the great bend of the Oxus northwards, the river valley has Surveys. been surveyed by Woodthorpe; and the northern slopes of the Hindu Kush, which near Ishkashim extend in slopes of barely 10 m. in length from the main watershed to the river banks, have been carefully mapped. These slopes represent the extent of Afghan territory which exists north of the Hindu Kush between Kala Panja and Ishkashim. From Ishkashim northwards the river passes through the narrow rock-bound valleys of Shignan and Roshan ere it sweeps north and west through the mountains and defiles of Darwaz. By the terms of the boundary agreement with Russia this part of the river now parts Badakshan and Darwaz from the districts of Roshan, Shignan, and Bokhara, which formerly maintained an uncertain claim over a part of the territory on the left bank of the river. All this part of the Oxus, until the river once again emerges from the Bokhara hills into the open plains bordering Badakshan on the north, falls within the area of Russian surveys, with which a junction from India has been effected both on the Pamirs and in Turkestan.

At Langar Kisht, a little to the east of the Oxus bend, there is a small Russian post of observation. About 50 m. north of the bend, where the Suchan or Ghund joins the Oxus from the Alichur Pamir, there is another and larger post called Charog. On the left bank of the river the Afghans main- the Oxus. tain a frontier post at the fort of Kala Bar Panja. A road will connect Charog with the Alichur Pamir, following the general course of the Ghund stream, a road which will form a valuable link in the chain of communications between Bokhara and Sarikol. Eighty-five miles north of Ishkashim, at Kala Wamar, the river which rises in the Little Pamir, and which is called Aksu, Murghab, or Bartang, joins the Oxus from the east. It is on this river that the Russian outpost, Murghabi (or Pamirski), is situated, at an elevation of 12,150 ft. above the sea. Fort Murghabi is connected by a good military road with Osh. At this point the measurement of the comparative lengths of the chief Pamir tributaries of the Oxus is as follows: To the head of the Aksu at Lake Chakmaktin. 260 miles. To the head of the most easterly tributary of Lake Victoria, in the Great Pamir, about. 230 „ To the glacial sources of the Ab-i-Wakhjir, about. 230 „ For 120 m. the two latter are united in the main stream of the Oxus, the volume of which has been further increased by the united forces of the Ghur d and Shakhdara draining the Alichur Pamir and the heights of Shignan.

The narrow cramped valley of the river between Ishkashim and Kala Wamar is hedged in on the west by a long ridge flanking the highlands of Badakshan; on the east the buttresses and Nature of spurs of the Shignan mountains (of which the strike is the Oxus transverse to the direction of the river and more or less Valley.. parallel to that of the main Hindu Kush watershed) overhang its channel like a wall, and afford but little room either for cultivation or for the maintenance of a practicable road. Yet the lower elevation (for this part of the Oxus stream is not more than about 7000 ft. above sea-level) and comparatively mild climate give opportunities to the industrious Tajik population for successful agriculture, of which they are not slow to avail themselves, and a track exists on the left bank of the river to Kala Bar Panja opposite the Ghund (or Suchan) debouchment, which is practicable for mules. There are no bridges, and the transit of the river from bank to bank can only be effected by the use of inflated skins. Beyond the Bartang (or Murghab) confluence the valley narrows, and the difficulties of the river route increase. Between Kala Wamar (6580 ft.) and Kala Khum (4400 ft.), where the Oxus again bends southwards, its course to the north-west is almost at right angles to the general strike of the Darwaz mountains, which is from north-east to south-west, following the usual conformation of all this part of high Asia. Thus its chief affluents from the northeast, the Wanj and the Yaz Ghulam, drain valleys which are comparatively open, and which are said to be splendidly fertile. At Kala Khum the river is 480 ft. wide, narrowing to 350 ft. in the narrowest gorge. Its level varies with the obstructions formed by ice, falling as much as 28 ft. when its upper channels are blocked.

The climate of eastern Bokhara and Darwaz is delightful in summer, and Dr Regel writes of its Alpine scenery and flora in terms of enthusiastic admiration. In the valleys of the Waksh and Pro- and the Surkhab to the north of Darwaz, which form an important part of the province of Karategin, maple, ash, hawthorn, pistachio, and juniper grow freely in the mountain forests, and beetroot, kohl rabi, and other vegetables are widely cultivated. About the cliffs and precipices of the Panja valley near Kala Khum the wild vine, cerasus, and pomegranate are to be found, and the plane tree and mulberry flourish in groups near the villages. Here also, amongst other plants, the sunflower decorates village gardens. The houses are built of stone and mortar, and above the thatched straw roof which surmounts the doublestoreyed buildings the square water-tower rises gracefully. Every house possesses its staircase, its well, and cisterns for irrigation; and on the whole the Aryan Tajiks of this northern section of the Oxus valley seem to be well provided with most of the comforts, if not the luxuries, of life. Their language is the language of Bokhara and Samarkand. Bokharan supremacy was re-established in 1878, when Kala Khum was occupied by Bokharan troops. Since then the right bank of the river has been politically divided from the left, and the latter now belongs to Afghanistan.

From Kala Khum, which fort about marks the most northerly point of the great bend of the Oxus round Badakshan, the river follows a south-westerly course for another 50 m. through a close mountainous region ere it widens into the more open valley to the south of Kolab. It now becomes a river of the plains from which the mountains on either side stand back. The topography of Darwaz south of the river is not accurately known, but at least one considerable stream of some 60 m. in length drains to the north-east, parallel to the general strike of the mountain system into the transverse course of the Oxus, which it joins nearly opposite to the lateral valleys of Yaz Ghulam and Wanj. ' This stream is called Pangi-Shiwa, or Shiwa, but not much is known about it. Another of about equal length, starting from the same, central water-parting of this mountain block, and included within the Oxus bend, follows a transverse direction at almost right angles to the Shiwa, and joins the Oxus valley near its debouchment into the more open Kolab plains, where the course of the Oxus has again assumed a direction parallel to the mountain strike. All that we know about this river (which is called the Ragh or Sadda) is that towards its junction with the Oxus it cuts through successive mountain ridges, which renders its course impracticable as a roadway. It is necessary to avoid the river, and to pass by mountain tracks which surmount a series of local spurs or offshoots from the central plateau, in order to reach the Oxus. The existence of this route, which traverses the Darwaz mountains from east to west, cutting off the northern bend of the Oxus, and connecting those easterly routes which intersect the Pamirs by means of the Ghund and Shakhdara (and which concentrate about Lake Shiwa) with Kolab in eastern Bokhara, is important. (See Badakshan.) From about the point where the Oxus commences to separate the Bokharan province of Kolab from the comparatively open Afghan districts of Rustak and Kataghan, the channel of the river is no longer confined within walls of mountains of volcanic and schistose formation. The Kolab and the Surkhab (or Waksh) flow into it in broad muddy streams from the highlands of Karateghin, and the river at once commences to adopt an uncertain channel wherever the outstretched arms of the hills fail to confine it within definite limits. It divides its waters, splitting into many channels, leaving broad central islands; and as the width increases, and the depth during dry seasons diminishes, opportunities for fords become comparatively frequent. Between Kolab and Pata Kesar, immediately north of the Turkestan capital of Mazar-i-Sharif, there are at least three wellknown "guzars" or fords, and there are probably more. Besides the great muddy affluents from Karateghin on the north, the Kabadian, the Surkhan, and the Darbant are all of them very considerable tributaries from Bokhara. The last of the three is the river on which the well-known trade centre of Shirabad is built, some 20 m. north of the river. Near the junction of the Surkhan with the Oxus are the ruins of the ancient city of Termez, on the northern or Bokharan bank, and the ferry at Pata Kesar (not far from the ruins of an old bridge) is the connecting link between Bokhara and Mazar hereabouts. A Russian branch railway is said to have been recently built from Samarkand to Termez.

From the south two very remarkable affluents of the Oxus join their streams to the main river between Kolab and the Mazar crossings. The Kokcha and the Khanabad (or Kunduz) are the two great rivers of Badakshan. The valley of the Kokcha leads directly from the Oxus to Faizabad, the capital of Badakshan, and its head is close above Ishkashim at the southern elbow of the great Oxus bend, a low pass of only 95 00 ft. dividing its waters from those of the main river. This undoubtedly was a section of the great central trade route of Asia, which once connected Ferghana and Herat with Kashgar and China. (See Badakshan.) Both these rivers tap the northern slopes of the Hindu Kush, and claim their sources in the unmapped mountain wilderness of Kafiristan. The Khanabad, or Kunduz, is also called locally the Aksarai. All the rivers of Central Asia are known by several names. To the west of the Kunduz no rivers find their way through the southern banks of the Oxus. Throughout the plains of Afghan Turkestan the drainage from the southern hills is arrested and lost in the desert sands.

The only island of any size in the bed of the river is the island of Paighambar, a little below the ruins of Termez. The inhabitants of this island, and of a smaller one in the neighbourhood called Zarshoi, wash for gold in the bed of the river.

At Airatan, a little above the Pata Kesar ferry, there are ruins, as also at Khisht Tapa (where the road from Kabadian to Tashkurghan leaves the river) and at Kalukh Tapa. At Khisht Tapa there is a tradition of a bridge having once existed.

The Oxus river, as seen in flood at this part of its course, is an imposing stream. It is rarely less than moo yards wide, and in some places it is fully a mile across. Its winter channel may be estimated at from two-thirds to three-fourths of its flood channel, except where it is confined within narrow limits by a rocky bed, as at Kilif, where its un varying width is only 540 yards. The average strength of the current in flood is about 4 m. per hour, varying from 22 to 5 m. The left bank of the Oxus above Kilif is, as a rule, low and flat, with reed swamps bordering the stream and a strip of jungle between the reeds and the edge of the elevated sandy desert. The jungle is chiefly tamarisk and padah (willow). Swamp deer, pheasants, and occasionally tigers are found in it. The right bank is generally higher, drier, more fertile and more populated;han the left.

A wide belt of blown sand (or Chul), sprinkled with sa.aul jungle, separates the swamps on the south side of the river from the cultivated plains of Afghan Turkestan; but in places, notably for Cultiva= about 12 Tn. above Khamiab, where the Russo-Afghan 6 °'boundary touches the river, through the districts which are best known by the name of Khwaja Salar, and again in a less degree for 50 m. above the ferry at Kilif, a very successful war has been waged by the agricultural Turkman (of the Ersari tribes) against the encroaching sand-waves of the desert; and a strip of riverain soil averaging about a mile in width has been reclaimed and cultivated by irrigation. The cultivation, supported by canals drawn from the Oxus, the heads of which are constantly being destroyed by flood and again renewed, is of a very high order. Wheat and barley spread in broad crops over many square miles of rich soil; the fields are intersected by narrow little stone-walled lanes, bright with wayside flowers, amongst which the poppy and the purple thistle of Badghis are predominant; the houses are neatly built of stone, and stand scattered about the landscape in single homesteads, substantial and comfortable; and the spreading willow and the mulberry offer a most grateful shade to the wayfarer in summer time, when the heat is often insupportable. The fiery blasts of summer, furnace-heated over the red-hot Kizil Kum, are hardly less to be feared than the ice-cold shamshir (or north-western blizzard) of winter, which freezes men when it finds them in the open desert, and frequently destroys whole caravans.

The principle on which the Oxus ferries are worked is peculiar to those regions. Large flat-bottomed boats are towed across the river by small horses attached to an outrigger projecting beyond the gunwale by means of a surcingle or bellyband. They are thus partially supported in the water whilst they swim. The horses are guided from the boat, and a twentyor thirty-foot barge with a heavy load of men and goods will be towed across the river at Kilif (where, as already stated, the width of the river is between 500 and 600 yards only) with ease by two of these animals. The Kilif ferry is on the direct high-road between Samarkand and Akcha. It is perhaps the best-used ferry on the Oxus.

Khwaja Salar derives some historical significance from the fact that it presented a substantial difficulty to the settlement of the RussoAfghan boundary, in which it was assigned by agreement as the point of junction between that boundary and the Khwaja Oxus. It had been defined in the agreement as a "post" Salar. on the river banks, and had been so described by Burnes in his writings some fifty years previously. But no post such as that indicated could be discovered. There was a district of that name extending from Khamiab to the neighbourhood of Kilif, and at the Kilif end of the district was a ziarat sacred to the Khwaja who bore the name. It was only after long inquiry amongst local cultivators and landowners that, about 2 m. below the ziarat, and nearly opposite to the site of the present Karkin bazaar, the position of a lost ferry was identified, which had once been marked by a riverside hamlet called by the name of the saint. The ferry had long disappeared, and with it a considerable slice of the riverside alluvial soil, which had been washed into the stream by the action of floods. The post had, in fact, subsided to the bottom of the river, but the consequences of its disappearance had been both far-reaching and expensive.

Below Khamiab, to its final disappearance in the Aral Sea, the great river rolls in silent majesty through a vast expanse of sand and desert. Under Russian auspices a considerable, strip of alluvial soil on the left bank has been brought under cultivation, measuring Lower 4 or 5 m. in width, and there is more cultivation on Go Oxus. the banks of the Oxus now than there is in the Mer y oasis O itself, but it is confined to the immediate neighbourhood of the river, for no affluents of any considerable size exist. The river is navigable below Charjui, and takes its place as an important unit in the general scheme of Russian frontier communications. There is now a regular steamer service, twice a week in summer and once a week in winter, as far as Pata Kasar. The steamers are flatbottomed paddle boats drawing 3 ft.

An important feature in connexion with the course of the Oxus is the discussion that has arisen with regard to its former debouch- Junction ment into the Caspian Sea. On this point much recent with evidence has been collected, and it appears certain that w Sea. there was a time in the post-Pliocene Age when a long Aral gulf of the Caspian Sea protruded eastwards nearly as far as the longitude of Merv, covering the Kara Kum sands, but not the Kara Kum plateau to the north of the sands, which is separated from the sands by a distinct sea beach. At the same time another branch of the same gulf protruded northwards in the direction of the Aral, probably as far as the Sary Kamish depression, which lies to the west of the Khivan delta of the Oxus, separated from it by wide beds of loess, clays and gravel, covering rocks of an unknown age. The Murghab river and the Hari Rud, which terminate in the oases of Mer y and Sarakhs, almost certainly penetrated to the gulf of the Kara Kum, but the question whether the Oxus was ever deflected so as to enter the gulf with the Murghab cannot be said to be answered decisively at present. The former connexion between the Caspian and Aral by means of the gulf now represented by the Sary Kamish depression seems to be admitted by Russian scientists, nor would there appear to be much doubt about the connexion between the Khivan oasis and the northern extremity of the Sary Kamish. In this discussion the names of Kaulbars, Lessar, Annenkov, Konshin and other Russian geographers are conspicuous. The general conclusions are ably summed up by P. Kropotkin in the September number of the Journal of the Royal Geographical Society for 1898.


In the most remote ages to which written history carries us, the regions on both sides of the Oxus were subject to the Persian monarchy. Of their populations Herodotus mentions the Bactrians, Chorasmians, Sogdians and Sacae as contributing their contingents to the armies of the great king Darius. The Oxus figures in Persian romantic history as the limit between Iran and Turan, but the substratum of settled population to the north as well as the south was probably of Iranian lineage. The valley is connected with many early Magian traditions, according to which Zoroaster dwelt at Balkh, where, in the 7th century B.C., his proselytizing efforts first came into operation. Buddhism eventually spread widely over the Oxus countries, and almost entirely displaced the religion of Zoroaster in its very cradle. The Chinese traveller Hsuen Tsang, who passed through the country in A.D. 630-644, found Termez, Khulm, Balkh, and above all Bamian, amply provided with monasteries, stupas and colossal images, which are the striking characteristics of prevalent Buddhism; even the Pamir highlands had their monasteries.

Christianity penetrated to Khorasan and Bactria at an early date; episcopal sees are said to have existed at Mer y and Samarkand in the 4th and 5th centuries, and Cosmas (c. 545) testifies to the spread of Christianity among the Bactrians and Huns.

Bactria was long a province of the empire which Alexander the Great left to his successors, but the Greek historians give very little information of the Oxus basin and its inhabitants. About 250 B.C. Diodotus, the "governor of the thousand cities of Bactria," declared himself king, simultaneously with the revolt of Arsaces which laid the foundation of the Parthian monarchy. The Graeco-Bactrian dominion was overwhelmed entirely about 126 B.C. by the Yue-chi, a numerous people who had been driven westwards from their settlements on the borders of China by the Hiungnu (q.v.). From the Yue-chi arose, about the Christian era, the great Indo-Scythian dominion which extended across the Hindu Kush southwards, over Afghanistan and Sind. The history of the next five centuries is a blank. In 571 the Haiathalah (Ephthalites, q.v.) of the Oxus, who are supposed to be descendants of the Yue-chi, were shattered by an invasion of the Turkish khakan; and in the following century the Chinese pilgrim Hsuen Tsang found the former empire of the Haiathalah broken up into a great number of small states, all acknowledging the supremacy of the Turkish khakan, and several having names identical with those which still exist. The whole group of states he calls Tukhara, by which name in the form Tokharistan, or by that of Haiathalah, the country continued for centuries to be known to the Mahommedans. At the time of his pilgrimage Chinese influence had passed into Tokharistan and Transoxiana. Yazdeged, the last of the Sassanid kings of Persia, who died in 651, when defeated and hard pressed by the Moslems, invoked the aid of China; the Chinese emperor, Taitsung, issued an edict organizing the whole country from Ferghana to the borders of Persia into three Chinese administrative districts, with 126 military cantonments, an organization which, however, probably only existed on paper.

In 711-712 Mahommedan troops were conducted by Kotaiba, the governor of Khorasan, into the province of Khwarizm (Khiva), after subjugating which they advanced on Bokhara and Samarkand, the ancient Sogdiana, and are said to have even reached Ferghana and Kashgar, but no occupation then ensued. In1016-1025the government of Khwarizm was bestowed by Sultan Mahmud of Ghazni upon Altuntash, one of his most distinguished generals.

Tokharistan in general formed a part successively of the empires of the Sassanid dynasty (terminated A.D. 999), of the Ghaznevid dynasty, of the Seljuk princes of Persia and of Khorasan, of the Ghbri or Shansabanya kings, and of the sultans of Khwarizm. The last dynasty ended with Sultan Jalal-ud-din, during whose reign (1221-1231) a division of the Mogul army of Jenghiz Khan first invaded Khwarizm, while the khan himself was besieging Bamian; Jalal-ud-din, deserted by most of his troops, retired to Ghazni, where he was pursued by Jenghiz Khan, and again retreating towards Hindustan was overtaken and driven across the Indus.

The commencement of the 16th century was marked by the rise of the Uzbeg rule in Turkestan. The Uzbegs were no one race, but an aggregation of fragments from Turks, Mongols and all the great tribes constituting the hosts of Jenghiz and Batu. They held Kunduz, Balkh, Khwarizm and Khorasan, and for a time Badakshan also; but Badakshan was soon won by the emperor Baber, and in 1529 was bestowed on his cousin Suleiman, who by 1555 had established his rule over much of the region between the Oxus and the Hindu Kush. The Mogul emperors of India occasionally interfered in these provinces, notably Shah Jahan in 1646; but, finding the difficulty of maintaining so distant a frontier, they abandoned it to the Uzbeg princes. About 1765 the wazir of Ahmad Shah Abdali of Kabul invaded Badakshan, and from that time until now the domination of the countries on the south bank of the Oxus from Wakhan to Balkh has been a matter of frequent struggles between Afghans and Uzbegs.

The Uzbeg rule in Turkestan has during the last fifty years been rapidly dwindling before the growth of Russian power. In 1863 Russia invaded the Khokand territory, taking in rapid succession the cities of Turkestan, Chimkent and Tashkend. In 1866 Khojend was taken, the power of Khokand was completely crushed, a portion was incorporated in the new Russian province of Turkestan, while the remainder was left to be administered by a native chief almost as a Russian feudatory; the same year the Bokharians were defeated at Irdjar. In 1867 an army assembled by the amir of Bokhara was attacked and dispersed by the Russians, who in 1868 entered Samarkand, and became virtually rulers of Bokhara. In 1873 Khiva was invaded, and as much of the khanate as lay on the right bank of the Oxus was incorporated into the Russian empire, a portion being afterwards made over to Bokhara. Russia acquired the right of the free navigation of the Oxus throughout its entire course, on the borders of both Khiva and Bokhara. The administration of the whole of the states on the right bank of the Oxus, down to the Russian boundary line at Ichka Yar, is now in the hands of Bokhara, including Karateghin - which the Russians have transferred to it from Khokand - and Darwaz at the entrance to the Pamir highlands.

AUTHoRITIEs.-Although much has been written of late years about the sources of the Oxus within the region of the Pamirs, there is very little to be found in the writings of geographers of modern date descriptive of that part of its course which separates Darwaz and Afghan Turkestan from Bokhara, and that little is chiefly in the pages of reports and gazettes, &c., which are not available to the public. The following authorities may be consulted: The Report of the Pamir Boundary Commission of 1895, published at Calcutta (1897); Dr A. Regel, "Journey in Karateghin and Darwaz," Investia, Russian Geog. Soc., vol. xiii. (1882); translation, vol. iv. Proc. R.G.S.; Michell, "Regions of the Upper Oxus," vol. vi. Proc. R.G.S. (1884); Griesbach, "Geological Field Notes," No. 3, Afghan Boundary Commission (1885); C. Yate, Northern Afghanistan (London, 1888); Curzon, "The Pamirs," vol. viii. Jour. R.G.S. (1896); Kropotkin, "Old Beds of the Oxus," Jour. R.G.S. (September 1898); Cobbold, Innermost Asia (London, 1900). To the above may be added the Reports of the Russo-Afghan Boundary Commission of 1884-1885, and that of Lockhart's Mission in 1885, and the Indian Survey Reports. (T. H. H.*) 0 Xygen (symbol 0, atomic weight 16), a non-metallic chemical element. It was apparently first obtained in 1727 by Stephen Hales by strongly heating minium, but he does not seem to have recognized that he had obtained a new element, and the first published description of its properties was due to J. Priestley in 1774, who obtained the gas by igniting mercuric oxide, and gave it the name "dephlogistigated air." K. W. Scheele, working independently, also announced in 1775 the discovery of this element which he called "empyreal air" (Crells' Annalen, 1785, 2, pp. 229, 291). A. L. Lavoisier repeated Priestley's experiments and named the gas "oxygen" (from Gr. OV)s, sour, yevv&cw, I produce) to denote that in a large number of cases, the products formed by the combustion of substances in the gas were of an acid character. Oxygen occurs naturally as one of the chief constituents of the atmosphere, and in combination with other elements it is found in very large quantities; it constitutes approximately eight-ninths by weight of water and nearly one-half by weight of the rocks composing the earth's crust. It is also disengaged by growing vegetation, plants possessing the power of absorbing carbon dioxide, assimilating the carbon and rejecting the oxygen. Oxygen may be prepared by heating mercuric oxide; by strongly heating manganese dioxide and many other peroxides; by heating the oxides of precious metals; and by heating many oxy-acids and oxy-salts to high temperatures, for example, nitric acid, sulphuric acid, nitre, lead nitrate, zinc sulphate, potassium chlorate, &c. Potassium chlorate is generally used and the reaction is accelerated and carried out at a lower temperature by previously mixing the salt with about one-third of its weight of manganese dioxide, which acts as a catalytic agent. The actual decomposition of the chlorate is not settled definitely; the following equations give the results obtained by P. F. Frankland and Dingwall (Chem. News, 188 7, 55, p. 67):-at a moderate heat: 8KC103= 5KC104-I-3KC1+202, succeeded by the following reactions as the temperature increases: 2KC10 3 =KC10 4 +KC1+0 2 and 2KC10 3 =2KC1+30 2 (see also F. Teed, ibid., 188 7, 55, p. 91; H. N. Warren, ibid., 1888, 58, p. 247; W. H. Sodeau, Proc. Chem. Soc., 1901, 17, p. 149). It may also be obtained by heating manganese dioxide or potassium bichromate or potassium permanganate with sulphuric acid; by the action of cobalt salts or manganese dioxide on a solution of bleaching powder (Th. Fleitmann, Ann., 1865, 134, p. 64); by the action of a ferrous or manganous salt with a salt of cobalt, nickel or copper on bleaching powder (G. F. Jaubert, Ger. pat. 157171); by passing chlorine into milk of lime (C. Winkler, Jour. prakt. Chem., 1866, 9 8, p. 340); by the action of chlorine on steam at a bright red heat; by the decomposition of hydrogen peroxide by bleaching powder, manganese dioxide, potassium ferricyanide in alkaline solution, or potassium permanganate in acid solution; by heating barium peroxide with an aqueous solution of potassium ferricyanide (G. Kassner, Zeit. angew. Chem., 1890, p. 448) Ba02+2K 3 Fe(CN) 6 =Ba[FeK 3 (CN) 6) 2 +0 2; by the decomposition of sodium and potassium peroxides with a solution of potassium permanganate in the presence of a trace of nickel salts (G. F. Jaubert, Comptes rendus, 1902, 134, P. 778).

Numerous methods have been devised for the manufacture of oxygen. The more important are as follows: by decomposing strongly heated sulphuric acid in the presence of a contact substance; by heating an intimate mixture of one part of sodium nitrate with two parts of zinc oxide (T. H. Pepper, Dingler's Jour., 1863, 167, p. 39): 2Zn0-1-4NaN03= 2Zn(ONa) 2 +2N 2 +50 2; by the use of cuprous chloride which when mixed with clay and sand, moistened with water and heated in a current of air at 100-200° C. yields an oxychloride, which latter yields oxygen when heated to 400° C (A. Mallet, Comptes rendus, 1867, 64,' p. 226; 1868, 66, p. 349); by the electrolysis of solutions of sodium hydroxide, using nickel electrodes; by heating calcium plumbate (obtained from litharge and calcium carbonate) in a current of carbon dioxide (G. Kassner, Monit. Scient., 1890, pp. 503, 614); and from air by the process of Tessie du Motay (Ding. Jour., 1870, 196, p. 230), in which air is drawn over a heated mixture of manganese dioxide and sodium hydroxide, the sodium manganate so formed being then heated to about 450° C. in a current of steam, the following reversible reaction taking place: 4NaOH+2Mn02+ 022Na2Mn04+2H20. Oxygen is largely prepared by Brin's process (Mein. soc. des Ingen. civ., 1881, p. 450) in which barium monoxide is heated in a current of air, forming the dioxide, which when the retorts are exhausted yields up oxygen and leaves a residue of monoxide; but this method is now being superseded, its place being taken by the fractional distillation of liquid air (The Times, Engin. Suppi., April 1 4, 1909, p. 13) as carried out by the Linde method (Eng. Pat. 14111; 1902).

Oxygen is a colourless, odourless and tasteless gas. It is somewhat heavier than air, its specific gravity being 1.10523 (A. Leduc, Comptes rendus, 1896, 123, p. 805). It is slightly soluble in water and more so in alcohol. It also dissolves quite readily in some molten metals, especially silver. Oxygen does not burn, but is the greatest supporter of combustion known, nearly all the other elements combining with it under suitable conditions (cf. Oxide). These reactions, however, do not take place if the substances are absolutely dry. Thus H. B. Baker (Proc. Chem. Soc., 1902, 18, p. 40) has shown that perfectly dry oxygen and hydrogen will not combine even at a temperature of 1000° C. It is the only gas capable of supporting respiration. For the properties of liquid oxygen see Liquid Gases.

It is found, more especially in the case of organic compounds, that if a substance which oxidizes readily at ordinary temperature be mixed with another which is not capable of such oxidation, then both are oxidized simultaneously, the amount of oxygen used being shared equally between them; or in some cases when the substance is spontaneously oxidized an equivalent amount of oxygen is converted into ozone or hydrogen peroxide. This phenomenon was first noticed by C. F. Schonbein (Jour. prakt. Chem., 1858-1868), who found that on oxidizing lead in the presence of sulphuric acid, the same quantity of oxygen is used to form lead oxide as is converted into hydrogen peroxide. In a similar manner M. Traube (Ber., 1882-1893) found that when zinc is oxidized in presence of water equivalent quantities of zinc hydroxide and hydrogen peroxide are formed at first, thus: Zn+H 2 O+0 2 =ZnO+H 2 0 2, followed by ZnO+H 2 O=Zn(OH) 2 ,Zn+H 2 O 2 =Zn(OH) 2. The oxygen uniting with the substance undergoing oxidation is generally known as "bound oxygen," whilst that which is transformed into ozone or hydrogen peroxide is usually called "active oxygen." C. Engler (Ber., 1897, 30, p. 1669) calls the substance which undergoes oxidation the "autoxidizer" and the substance which unites with the active oxygen the "acceptor"; in the oxidation of metals he expresses results as: M+02=M02, followed by MO,-)M0+0, and if water be present, 0+H 2 O, ---11202. Various theories have been developed in order to account for these phenomena. Schonbein (loc. cit.) assumed that the ordinary oxygen molecule is decomposed into two parts which carry electrical charges of opposite kinds, the one with the positive charge being called "antozone" and the other carrying the negative charge being called "ozone," one variety being preferentially used up by the oxidizing compound or element and the other for the secondary reaction. J. H. Van't Hoff (Zeit. phys. Chem., 1895, 16, p. 411) is of the opinion that the oxygen molecule is to a certain extent ionized and that the ions of one kind are preferably used by the oxidizing compound. Traube (loc. cit.), on the other hand, concludes that the oxygen molecule enters into action as a whole and that on the oxidation of metals, hydrogen peroxide and the oxide of the metal are the primary products of the reaction. A. Bach (Comptes rendus, 1897, 124, p. 2) considers that the first stage in the reaction consists in the production of a peroxide which then interacts with water to form hydrogen peroxide (see also W. Manchot, Ann., 1901, 3 1 4, p. 1 77; 1902, 3 2 5, p. 95).

Oxygen is a member of the sixth group in the periodic classification, and consequently possesses a maximum valency of six. In most cases it behaves as a divalent element, but it may also be quadrivalent. A. v. Baeyer and V. Villiger (Be y ., 1901, 34, pp. 2679, 3612) showed that many organic compounds (ethers, alcohols, aldehydes, ketones, &c.) behave towards acids, particularly the more complex acids, very much like bases and yield crystallized salts in which quadrivalent oxygen must be assumed as the basic element. These salts are considered to be derived from the hypothetical base OH 3. OH, oxonium hydroxide (compare sulphonium salts). Further see J. Schmidt, "Uber die basischen Eigenschaften des Sauerstoffs" (Berlin, 1904). Baeyer and Villiger assume for the configuration of the salts of carbonyl compounds the arrangement > C: 0 < whilst, W. Bruhl and P. W. Walden point out from the physico-chemical standpoint that in water and hydrogen peroxide the oxygen atom is probably quadrivalent.

The atomic weight of oxygen is now generally taken as 16, and as such is used as the standard by which the atomic weights of the other elements are determined, owing to the fact that most elements combine with oxygen more readily than with hydrogen (see ELE Ment).

Oxygen is widely used in medical practice as well as in surgery. Inhalations of the gas are of service in pneumonia, bronchitis, heart disease, asthma, angina and other conditions accompanied by cyanosis and dyspnoea. They often avert death from asphyxia, or render the end less distressing. Oxygen is also administered in chloroform poisoning, and in threatened death from the inhalation of coal gas or nitrous oxides. It is of value in cyanide and opium poisoning and in the resuscitation of the apparently drowned. The mode of administration is by an inhaler attached to an inhalation bag, which serves to break the force with which the oxygen issues from the cylinders in which it is sold in a compressed form. It can be administered pure or mixed with air as required. If given in too great quantity a temporary condition of apnoea (cessation of breathing) is produced, the blood being fully charged with the gas. Oxygen may be applied locally as a disinfectant to foul and diseased surfaces by the use of the peroxide of hydrogen, which readily parts with its oxygen; a solution of hydrogen peroxide therefore forms a valuable spray in diphtheria, tonsillitis, laryngeal tuberculosis and ozaena. It can also be used with advantage in inoperable uterine cancer, favus and lupus, and as an injection in gonorrhoea and suppurative conditions of the ear. It relieves the pain of wasp and bee stings. Internally hydrogen peroxide is used in various diseased conditions of the gastro-intestinal tract, such as dyspepsia, diarrhoea and enteric fever. The B.P. preparation Liquor Hydrogenii Peroxidi dose i to 2 drs. is synonymous with the Aqua Hydrogenii Dioxidi of the U.S.P. and the ten-volume solution termed eau oxygenee in France. It is customary to use oxygen in combination with chloroform, or nitrous oxide in order to produce insensibility to pain (see Anaesthetics).

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