or AMME. This great river of Central Asia has its source in the high lands of Pamir, a branch of the main ridge of the Hindu Coosh Mountains, which, extending northward, forms the boundary between Tibet and Great Bukharia. It issues from a glacier in a narrow valley 200 or 300 yards broad, which is enclosed on three sides by the high snowy mountain called Pooshtkhir. The stream is seen flowing from under the ice, which is stated to be at least forty spears in depth. The spring itself is buried under the great mass of ice whence it issues, and cannot be seen; but there is no doubt of its issuing from this spot, as there is no other open or break from which it could issue at any more distant point. The small but swelling stream is carried north in this narrow valley for five coss or ten miles; at eight miles it is twenty yards broad, and breast deep; and on leaving the valley, after being joined by many other springs from the same hill, it is fifty yards broad, and about four feet deep. It is joined by the Siiber about sixty miles from its source, which is sixty yards broad. The Oxus, however, is much broader, having been joined by seven or eight streams from knee to middle deep, and from ten to thirty yards broad. It flows in a south-west direction for 120 miles, and then meets a high ridge of mountains running from west-north-west to east-south-east. From this point it takes a west-south-west course through the wild and mountainous regions which separate the country of Balkh from Independent Tartary, until it breaks through the ridge in its progress southward, and meets some of the ridges which diverge from the main ridge of Hindu Coosh. In this part of its upper course, being a distance of more than 300 miles, it is confined between the mountains, and is joined by numerous streams, from two to four of which are crossed in each day's journey along its left or southern bank, besides two very considerable rivers, namely, the Soorkhab or Kurategeen River, and the Kokcha or Budukshan River. It also receives the tribute of many streams from the north, the names of which are unknown in Europe. Its course is now west-north-west; and it passes the far-famed city of Samarcand, which, however, is not situated on its banks, but on a river flowing into it. To Bukharia, which is situated on one of its tributary streams, it has a northerly course of 250 miles, being forced off in this direction by the high land of Hindu Coosh, which extends north of the ridge a considerable distance, and runs over a flat country, sandy, and little better than a desert. From this point to Ourgunge is a distance of 400 miles, over a desert of at least 300 miles, with only a few habitations of horse-breeders along the banks. On the left bank is a forest the greater part of the way, through which those who pass are obliged to carry their provisions for eight or ten days at a time. Mr Elphinstone has thus traced OXYCRATE its course for 900 miles; and other travellers in the East have gleaned scanty information respecting its lower course till it terminates in the Sea of Aral after a course of 1200 miles. Frazer mentions, on the authority of a native traveller or merchant, that after passing the town of Ourgunge, it makes a turn to the east, and is joined by the Seer or Sihon (the Jaxartes), when both spread out into a large lake, which has no outlet, its waters being absorbed by the sand of which the surrounding country is composed. Frazer seems to think that this account corresponds so well with that of the Arabian and the Persian geographers, that there is no denying credit to it. But the accounts of native travellers are proverbially so erroneous, that no reliance can be placed upon them. They generally travel for the purposes of trade, and pay little attention to the geography of the country, or other details; and this, joined to their known carelessness of truth, renders their testimony of little value. Colonel Kinneir mentions, that Sir John Malcolm conversed with a native, who assured him that the termination of the river was in the Caspian Sea. This opinion is, however, strongly combated by Mr Frazer, who affirms that there is nothing like evidence to prove that the Oxus ever reached the Caspian Sea; that this notion rests on vague tradition, founded on ignorance; and that all the native authorities who speak directly to this point constantly say that the Jeyhoon or Ammu falls into the lake of Kharezm. The ancient geographers were ignorant that there were two distinct lakes in Asia, namely, the Caspian Sea, and that of Aral. They supposed that both formed one lake; and hence their error was extremely natural, in giving a termination to the Oxus in the Caspian, the only outlet which they knew to exist in the direction of its stream. But we know for certain that no river falls into the Caspian to the south of the bay of Mangulshuck; for the caravans that pass and repass from Astrabad to Khyvah, and from thence to Mangulshuck, do not cross a single stream, or meet with a drop of running fresh water, after crossing the river Attruk near Astrabad. It is equally certain, from the same evidence, that no branch of the Oxus falls into the Caspian to the northward of Mangulshuck. Mr Frazer, in answer to his inquiries concerning the rise of the Oxus or Ammu, was informed by a traveller who saw it in the summer season near Balkh, that it was as large as the Junna in its fullest season, and perfectly navigable for boats, which are in common use for crossing the stream, and for the conveyance both of goods and passengers from Balkh and from Bukharia to Ourgunge and Khyvah. At Bukharia it is a very large river, the stream being at no time less than a thousand yards wide; and in summer, when the snow melts, it sometimes spreads to the breadth of four miles. It is deep, and navigable for boats, by which means an active intercourse is maintained in most parts of its course.

OXYCRATE, an old term in Pharmacy, denoting a mixture of vinegar and water, proper to assuage, cool, and refresh. The usual proportion is one spoonful of vinegar to five or six spoonfuls of water.

OXIDE, or Oxide, in Chemistry, is the term employed to denote a very numerous class of bodies formed by the union of certain bases with a smaller proportion of oxygen than what is necessary for their conversion into acids. See Chemistry.