BLACK SEA, a body of water between lat. 41O and 45° N., but extending to about 47° near Odessa, bounded north by south Russia ; west by Rumania, Bulgaria and Turkey ; and south and east by Asia Minor. It is also called Euxine (anc., Pontus Eux inns) ; the early Greek navigators named it axeinos ("hostile to strangers"), but with the growth of Greek colonies on its shores, it became Euxeinos ("friendly to strangers") . The northern boundary is broken at Kertch by a strait of the same name con necting it with the Sea of Azov, and at its south-west end it opens through the Bosporus, the Sea of Marmora and the Dar danelles to the Mediterranean. Its area of about 164,000sq.m. is approximately the same as that of the Baltic ; its average depth is much greater than that of the Baltic, namely, 65o fathoms. The greatest depth is 1,16o fathoms near the centre, there being only one basin. Large powerful rivers flow into the Black sea, the Danube, Dniester, Dnieper, Don, etc. The Black sea shows con ditions different from those of the Mediterranean or any other sea. The existence of sulphuretted hydrogen in great quantities below 8o fathoms (4cu.cm. per litre and more in the depths be low 35o fathoms), the extensive chemical precipitation of calcium carbonate, the stagnant nature of its deep waters and the absence of deep sea-life are highly peculiar features. Higher organic life is not known to exist below 8o fathoms. Fossil Dreissena, Car diunn and other molluscs have, however, been dredged up, which help to show that the Black sea was formerly much like the Cas pian to-day. According to N. Andrusov, when in an earlier geo logical period the union of Black sea and Mediterranean through the Bosporus took place, salt water rushed into it along the bot tom of the Bosporus and killed the fauna of the less saline waters. This produced sulphuretted hydrogen (H2S) which is found in the deposits, as well as in the deeper waters.
Another explanation of the existence of this sulphuretted hydrogen in the waters of the Black sea is based upon present conditions. This sea receives far more fresh water from rain and rivers than it loses by evaporation; the salt-content of the surface water in summer and in winter is therefore only 15 to (against 37 to in the Mediterranean) ; below 5o fathoms the water is more salt (20 to 2 and this salt water is largely brought by the undercurrent through the Dardanelles and Bos porus. This salter water occupies the deeps of the Black sea. Apart from two winter months the surface water is much warmer than the deep water and both temperature and relative freshness make the surface water comparatively light ; this holds good even in winter. This covering impermeable layer lies, therefore, like a coating of oil over the deep water of the Black sea and hinders gaseous exchange with the atmosphere ; the water below 5o fath oms receives no oxygen and the living organisms of the surface waters sinking after death into the deeps, their remains cannot be oxidized but decay into carbonic acid and sulphuretted hydro gen. However this may be, there is an immense depth of water in the Black sea (800 to 1,16o fathoms) without any organic life, a unique feature for the world's seas. This explanation is also supported by the fact that the coldest water (44-5°) is not on the sea floor as in the open ocean, but round about a depth of 5o fathoms. The cold winter water cannot sink below this, and this is the downward limit of life ; the water below is poisoned.
There is a counter-clockwise surface current in the Black sea and the surplus fresh water flows off from the Bosporus. Tides are hardly distinguishable. The climate is very harsh save in the sum mer months; strong cold north, north-east and north-west winds are dominant, especially in winter, when they give rise to fre quent severe storms. Only the south coast of the Crimea resem bles in any way the Mediterranean in climate. Clouds are com mon in spring. At Odessa there is ice on the sea for an average of 16 to 20 days in winter, in the Strait of Kertch for 41 days.
Black sea was formerly the name of a military district of the Kuban, Russia, now included in the N. Caucasian area (q.v.).
The Black Sea, the "Pontus Euxinus" of the Romans, has played an important part in the economic and political history of East ern Europe from earliest times. Across it sailed Jason to Colchis, the modern Georgia, in search of the Golden Fleece; and many legends of antiquity are,doubtless idealized versions of early com mercial or political ventures. With the establishment of Con stantinople as capital of the later Roman empire, the political and strategic importance of the Black sea was greatly increased. Merchandise from Persia and its adjacent lands was shipped from Trebizond to Constantinople, for distribution through Western Europe. Another great trade route led from the Baltic to the Crimea, and hence to Constantinople. The name Euxeinos, "hos pitable to strangers," was probably a propitiatory euphemism for the older Axenos, "inhospitable." With the capture of Constantinople by the Ottoman Turks in 1453, the trade of the Black sea suffered a set-back; soon, how ever, Italian, French, and, somewhat later, English traders, re vived commerce across its waters; and the system of Capitula tions (q.v.) instituted by the Ottoman Sultans enabled them to do so with some security. For nearly 3oo years the Black sea was virtually a Turkish lake. Its sole ingress and egress—the Bosporus and the Dardanelles—was controlled by the Porte, which levied dues upon all vessels passing the straits.
The situation changed after the accession of Peter the Great to the Russian throne. Peter was the first Russian tsar to ap preciate fully the importance of commercial enterprise in national life, and he made every effort to promote Russian trade with the East Mediterranean ports. He further recognized the im portance of a strong fleet to protect his traders both from the pirates then infesting the coasts of the Black sea and from pos sible Turkish depredations in case of war. He constructed arsenals in the Sea of Azov and the Crimea and laid the foundations of Russia's later naval strength in the Black sea. His successors carried on his policy, blending commercial enterprise with the more idealistic ambitions of Pan-Slavism (q.v.). As Russia's communications were improved and her commerce developed in the 19th century, the Black sea became more prominent in the eyes of Europe as a highway of commerce. To the corn and similar products of Southern Russia was presently added the oil of the Caspian; and the trade carried by the Black sea increased annually in value until 1914.
Partly to protect this commerce, partly for political purposes, Russia built up a strong Black sea fleet, fear of which, enter tained both at the Porte and in Western Europe, particularly in London, led to the imposition of Draconian restrictions upon Russian maritime enterprise in the Treaty of Paris, which con cluded the Crimean War (q.v.) in 1856. Fourteen years later, however, Russia seized the opportunity presented by the Franco Prussian War to repudiate these restrictions. From this date until 1914 Russia remained free to develop her naval resources in the Black sea.
During the i8th and i9th centuries Russia, Rumania and Bulgaria took the place of Turkey on the northern and western coasts of the Black sea. The Balkan Wars of 1912-13 slightly extended Rumania's frontier at the expense of Bulgaria; while in 1919 Rumania, besides receiving confirmation of this change, also received Bessarabia (q.v.) from Russia: a transference which the Soviet Government refused to recognize as valid. Further east, the Ukraine and Georgia took the place of Russia as riparian States, but as both remained parts of the U.S.S.R., the change was really one of internal organization only.
The Black sea trade suffered severely through the World War and its sequels in Russia. The export of corn from Rumania and Russia ceased altogether for some years. Russia's naval strength was also temporarily reduced, but later steps were taken to restore it.
For the diplomatic history of the Straits and the Dardanelles, see the article STRAITS. (See also RUSSIA; TURKEY ; EASTERN QUESTION ; CRIMEAN WAR ; PAN-SLAVISM.) (I. F. D. M.)