Part 44

BOPPARD, a town of Germany, in the Prussian Rhine province, on the left bank of the Rhine, 12 m. S. of Coblenz on the mainline to Cologne. Pop. (1900) 5806. It is an old town still partly surrounded by medieval walls, and its most noteworthy buildings are the Roman Catholic parish church (12th and 13th centuries); the Carmelite church (1318), the former castle, now used for administrative offices; the Evangelical church (1851, enlarged in 1887); and the former Benedictine motnastery of the Marienberg, founded 1123 and since 1839 a hydropathic establishment, crowning a hill 100 ft. above the Rhine. Boppard is a favourite tourist centre, and being less pent in by hills than many other places in this part of the picturesque gorge of the Rhine, has in modern times become a residential town. It has some comparatively insignificant industries, such as tanning and tobacco manufacture; its direct trade is in wine and fruit.

Boppard (_Baudobriga_) was founded by the Romans; under the Merovingian dynasty it became a royal residence. During the middle ages it was a considerable centre of commerce and shipping, and under the Hohenstaufen emperors was raised to the rank of a free imperial city. In 1312, however, the emperor Henry VII. pledged the town to his brother Baldwin, archbishop-elector of Trier, and it remained in the possession of the electors until it was absorbed by France during the Revolutionary epoch. It was assigned by the congress of Vienna in 1815 to Prussia.

BORA, an Italian name for a violent cold northerly and northeasterly wind, common in the Adriatic, especially on the Istrian and Dalmatian coasts. There is always a northern tendency in the winds on the north Mediterranean shores in winter owing to the cold air of the mountains sliding down to the sea where the pressure is less. When, therefore, a cyclone is formed over the Mediterranean, the currents in its north-western area draw the air from the cold northern regions, and during the passage of the cyclone the bora prevails. The bora also occurs at Novorossiysk on the Black Sea. It is precisely similar in character to the mistral which prevails in Provence and along the French Mediterranean littoral.

BORACITE, a mineral of special interest on account of its optical anomalies. Small crystals bounded on all sides by sharply defined faces are found in considerable numbers embedded in gypsum and anhydrite in the salt deposits at Luneburg in Hanover, where it was first observed in 1787. In external form these crystals are cubic with inclined hemihedrism, the symmetry being the same as in blende and tetrahedrite. Their habit varies according to whether the tetrahedron (fig. 1), the cube (fig. 2). or the rhombic dodecahedron (fig. 3) predominates. Penetration twins with a tetrahedron face as twin-plane are sometimes observed. The crystals vary from translucent to transparent, are possessed of a vitreous lustre, and are colourless or white, though often tinged with grey, yellow or green. The hardness is as high as 7 on Mohs' scale; specific gravity 3.0. As first observed by R.J. Hauy in 1791, the crystals are markedly pyroelectric; a cube when heated becomes positively electrified on four of its corners and negatively on the four opposite corners. In a crystal such as represented in fig. 3, the smaller and dull tetrahedral faces s are situated at the analogous poles (which become positively electrified when the crystal is heated), and the larger and bright tetrahedral faces _s'_ at the antilogous poles.

[Illustration: Fig. 1 Fig. 2 Fig. 3

Crystals of Boracite]

The characters so far enumerated are strictly in accordance with cubic symmetry, but when a crystal is examined in polarized light, it will be seen to be doubly refracting, as was first observed by Sir David Brewster in 1821. Thin sections show twin-lamellae, and a division into definite areas which are optically biaxial. By cutting sections in suitable directions, it may be proved that a rhombic dodecahedral crystal is really built up of twelve orthorhombic pyramids, the apices of which meet in the centre and the bases coincide with the dodecahedral faces of the compound (pseudo-cubic) crystal. Crystals of other forms show other types of internal structure. When the crystals are heated these optical characters change, and at a temperature of 265 deg. the crystals suddenly become optically isotropic; on cooling, however, the complexity of internal structure reappears. Various explanations have been offered to account for these "optical anomalies" of boracite. Some observers have attributed them to alteration, others to internal strains in the crystals, which originally grew as truly cubic at a temperature above 265 deg. It would, however, appear that there are really two crystalline modifications of the boracite substance, a cubic modification stable above 265 deg. and an orthorhombic (or monoclinic) one stable at a lower temperature. This is strictly analogous to the case of silver iodide, of which cubic and rhombohedral modifications exist at different temperatures; but whereas rhombohedral as well as pseudo-cubic crystals of silver iodide (iodyrite) are known in nature, only pseudo-cubic crystals of boracite have as yet been met with.

Chemically, boracite is a magnesium borate and chloride with the formula Mg7Cl2B16O30--A small amount of iron is sometimes present, and an iron-boracite with half the magnesium replaced by ferrous iron has been called huyssenite. The mineral is insoluble in water, but soluble in hydrochloric acid. On exposure it is liable to slow alteration, owing to the absorption of water by the magnesium chloride: an altered form is known as parasite.

In addition to embedded crystals, a massive variety, known as stassfurtite, occurs as nodules in the salt deposits at Stassfurt in Prussia: that from the carnallite layer is compact, resembling fine-grained marble, and white or greenish in colour, whilst that from the kainite layer is soft and earthy, and yellowish or reddish in colour. (L. J. S.)

BORAGE (pronounced like "courage"; possibly from Lat. _borra_, rough hair), a herb (_Borago officinalis_) with bright blue flowers and hairy leaves and stem, considered to have some virtue as a cordial and a febrifuge; used as an ingredient in salads or in making claret-cup, &c.

BORAGINACEAE, an order of plants belonging to the sympetalous section of dicotyledons, and a member of the series Tubiflorae. It is represented in Britain by bugloss (_Echium_) (fig. 1), comfrey (_Symphytum_), _Myosotis_, hounds-tongue (_Cynoglossum_) (fig. 2), and other genera, while borage (_Borago officinalis_) (fig. 3) occurs as a garden escape in waste ground. The plants are rough-haired annual or perennial herbs, more rarely shrubby or arborescent, as in _Cordia_ and _Ehretia_, which are tropical or sub-tropical. The leaves, which are generally alternate, are usually entire and narrow: the radical leaves in some genera, as _Pulmonaria_ (lungwort) and _Cynoglossum_, differ in form from the stem-leaves, being generally broader and sometimes heart-shaped. A characteristic feature is the one-sided (_dorsiventral_) inflorescence, well illustrated in forget-me-not and other species of _Myosotis_; the cyme is at first closely coiled, becoming uncoiled as the flowers open. At the same time there is often a change in colour in the flowers, which are red in bud, becoming blue as they expand, as in _Myosotis, Echium, Symphytum_ and others. The flowers are generally regular; the form of the corolla varies widely. Thus in borage it is rotate, tubular in comfrey, funnel-shaped in hounds-tongue, and salver-shaped in alkanet (_Anchusa_); the throat is often closed by scale-like outgrowths from the corolla, forming the so-called corona. A departure from the usual regular corolla occurs in _Echium_ and a few allied genera, where it is oblique; in _Lycopsis_ it is also bent.

[Illustration: FIG. 1.--Viper's Bugloss (_Echium vulgare_), about 1/4 nat. size.

1. Single flower, about nat. size. 6. Calyx surrounding nutlets. 2. Corolla split open. 7. Same part of calyx cut away. 3. Calyx. 8. Two nutlets. 4. Pistil. 9. Same enlarged.] 5. One stamen.

The five stamens alternate in position with the lobes of the corolla. The ovary, of two carpels, is seated on a ring-like disk which secretes honey. Each carpel becomes divided by a median constriction in four portions, each containing one ovule; the style springs from the centre of the group of four divisions.

[Illustration: FIG. 2.--(1) Inflorescence of Forget-me-not; (2) ripe fruits.]

The flowers show well-marked adaptation to insect-visits. Their colour and tendency to arrangement on one surface, with the presence of honey, serve to attract insects. The scales around the throat of the corolla protect the pollen and honey from wet or undesirable visitors, and by their difference in colour from the corolla-lobes, as in the yellow eye of forget-me-not, may serve to indicate the position of the honey. In most genera the fruit consists of one-seeded nutlets, generally four, but one or more may be undeveloped. The shape of the nutlet and the character of its coat are very varied. Thus in _Lithospermum_ the nutlets are hard like a stone, in _Myosotis_ usually polished, in _Cynoglossum_ covered with bristles, &c.

The order is widely spread in temperate and tropical regions, and contains 85 genera with about 1200 species. Its chief centre is the Mediterranean region, whence it extends over central Europe and Asia, becoming less frequent northwards. A smaller centre occurs on the Pacific side of North America. The order is less developed in the south temperate zone.

[Illustration: FIG. 3.--(1) Flower of Borage; (2) same in vertical section enlarged; (3) horizontal plan of flower; (4) flower of Comfrey after removal of corolla, showing unripe fruit.]

The order is of little economic value. Several genera, such as borage and _Pulmonaria_, were formerly used in medicine, and the roots yield purple or brown dyes, as in _Alkanna tinctoria_ (alkanet). Heliotrope or cherry-pie (_Heliotropium peruvianum_) is a well-known garden plant.

BORAS, a town of Sweden, in the district (_lan_) of Elfsborg, 45 m. E. of Gothenburg by rail, on the river Viske. Pop. (1880) 4723; (1900) 15,837. It ranks among the first twelve towns in Sweden both in population and in the value of its manufacturing industries. These are principally textile, as there are numerous cotton spinning and weaving mills, together with a technical weaving school. The town was founded in 1632 by King Gustavus Adolphus.

BORAX (sodium pyroborate or sodium biborate), Na2B4O7, a substance which appears in commerce under two forms, namely "common" or prismatic borax, Na_2B4O7.10H2O, and "jewellers'" or octahedral borax, Na_2B4O7.5H2O. It is to be noted that the term "borax" was used by the alchemists in a very vague manner, and is therefore not to be taken as meaning the substance now specifically known by the name. Prismatic borax is found widely distributed as a natural product (see below, _Mineralogy_) in Tibet, and in Canada, Peru and Transylvania, while the bed of Borax Lake, near Clear Lake in California, is occupied by a large mass of crystallized borax, which is fit for use by the assayer without undergoing any preliminary purification. The supply of borax is, however, mainly derived from the boric acid of Tuscany, which is fused in a reverberatory furnace with half its weight of sodium carbonate, and the mass after cooling is extracted with warm water. An alternative method is to dissolve sodium carbonate in lead-lined steam-heated pans, and add the boric acid gradually; the solution then being concentrated until the borax crystallizes. Borax is also prepared from the naturally occurring calcium borate, which is mixed in a finely divided condition with the requisite quantity of soda ash; the mixture is fused, extracted with water and concentrated until the solution commences to crystallize.

From a supersaturated aqueous solution of borax, the pentahydrate, Na2B4O7.5H2O, is deposited when evaporation takes place at somewhat high temperatures. The same hydrate can be prepared by dissolving borax in water until the solution has a specific gravity of 1.246 and then allowing the solution to cool. The pentahydrate is deposited between 79 deg. C. and 56 deg. C.; below this temperature the decahydrate or ordinary borax, Na2B4O7.10H2O, is deposited. Crystals of ordinary borax swell up to a very great extent on heating, losing their water of crystallization and melting to a clear white glass. The crystals of octahedral borax fuse more easily than those of the prismatic form and are less liable to split when heated, so that they are preferable for soldering or fluxing. Fused borax dissolves many metallic oxides, forming complex borates which in many cases show characteristic colours. Its use in soldering depends on the fact that solder only adheres to the surface of an untarnished metal, and consequently a little borax is placed on the surface of the metal and heated by the soldering iron in order to remove any superficial film of oxide. It is also used for glazing pottery, in glass-making and the glazing of linen.

Boric acid (q.v.) being only a weak acid, its salts readily undergo hydrolytic dissociation in aqueous solution, and this property can be readily shown with a concentrated aqueous solution of borax, for by adding litmus and then just sufficient acetic acid to turn the litmus red, the addition of a large volume of water to the solution changes the colour back to blue again. The boric acid being scarcely ionized gives only a very small quantity of hydrogen ions, whilst the base (sodium hydroxide) produced by the hydrolysis occasioned by the dilution of the solution, being a "strong base," is highly ionized and gives a comparatively large amount of hydroxyl ions. In the solution, therefore, there is now an excess of hydroxyl ions; consequently it has an alkaline reaction and the litmus turns blue.

_Mineralogy._--The Tibetan mineral deposits have been known since very early times, and formerly the crude material was exported to Europe, under the name of _tincal_, for the preparation of pure borax and other boron salts. The most westerly of the Tibetan deposits are in the lake-plain of Pugha on the Rulangchu, a tributary of the Indus, at an elevation of 15,000 ft.: here the impure borax (_sohaga_) occurs over an area of about 2 sq. m., and is covered by a saline efflorescence; successive crops are obtained by the action of rain and snow and subsequent evaporation. Deposits of purer material (_chu tsale_ or water borax) occur at the lakes of Rudok, situated to the east of the Pugha district; also still farther to the east at the great lakes Tengri Nor, north of Lhasa, and several other places. More recently, the extensive deposits of borates (chiefly, however, of calcium; see COLEMANITE) in the Mohave desert on the borders of California and Nevada, and in the Atacama desert in South America, have been the chief commercial sources of boron compounds. The boron contained in solution in the salt lakes has very probably been supplied by hot springs and solfataras of volcanic origin, such as those which at the present day charge the waters of the lagoons in Tuscany with boric acid. The deposits formed by evaporation from these lakes and marshes or salines, are mixtures of borates, various alkaline salts (sodium carbonate, sulphate, chloride), gypsum, &c. In the mud of the lakes and in the surrounding marshy soil fine isolated crystals of borax are frequently found. For example, crystals up to 7 in. in length and weighing a pound each have been found in large numbers at Borax Lake in Lake county, and at Borax Lake in San Bernardino county, both in California.

Borax crystallizes with ten molecules of water, the composition of the crystals being Na2B4O7 + 10H2O. The crystals belong to the monoclinic system, and it is a curious fact that in habit and angles they closely resemble pyroxene (a silicate of calcium, magnesium and iron). There is a perfect cleavage parallel to the orthopinacoid and less perfect cleavages parallel to the faces of the prism. The mineral is transparent to opaque and white, sometimes greyish, bluish or greenish in colour. Hardness 2-2-1/2; sp. gr. 1.69-1.72.

The optical characters are interesting, because of the striking crossed dispersion of the optic axes, of which phenomenon borax affords the best example. The optic figure seen in convergent polarized light through a section cut parallel to the plane of symmetry of a borax crystal is symmetrical only with respect to the central point. The plane of the optic axes for red light is inclined at 2 deg. to that for blue light, and the angle between the optic axes themselves is 3 deg. greater for red than for blue light.

BORDA, JEAN CHARLES (1733-1799), French mathematician and nautical astronomer, was born at Dax on the 4th of May 1733. He studied at La Fleche, and at an early age obtained a commission in the cavalry. In 1756 he presented a _Memoire sur le mouvement des projectiles_ to the Academy of Sciences, who elected him a member. He was present at the battle of Hastembeck, and soon afterwards joined the naval service. He visited the Azores and the Canary Islands, of which he constructed an admirable map. In 1782 his frigate was taken by a British squadron; he himself was carried to England, but was almost immediately released on parole and returned to France. He died at Paris on the 20th of February 1799. Borda contributed a long series of valuable memoirs to the Academy of Sciences. His researches in hydrodynamics were highly useful for marine engineering, while the reflecting and repeating circles, as improved by him, were of great service in nautical astronomy. He was associated with J.B.J. Delambre and P.F.A. Mechain in the attempt to determine an arc of the meridian, and the greater number of the instruments employed in the task were invented by him.

See J.B. Biot, "Notice sur Borda" in the _Mem. de l'Acad. des Sciences_, iv.

BORDAGE. (i) A nautical term (from Fr. _bord_, side) for the planking on a ship's side. (2) A feudal term (from Lat. _borda_, a cottage) for the tenure by which a certain class of villein held their cottages; also the services due from these villeins or "bordars." A "bordar" (Med. Lat. _bardarius_) was a villein who obtained a cottage from his lord in return for menial services (see VILLENAGE).

BORDEAUX, a city of south-western France, capital of the department of Gironde, 359 m. S.S.W. of Paris by a main line of the Orleans railway and 159 m. N.W. of Toulouse on the main line of the Southern railway. Pop. (1906) 237,707. Bordeaux, one of the finest and most extensive cities in France, is situated on the left or west bank of the Garonne about 60 m. from the sea, in a plain which comprises the wine-growing district of Medoc. The Garonne at this point describes a semicircle, separating the city proper on the left bank from the important suburb of La Bastide on the right bank. The river is crossed by the Pont de Bordeaux, a fine stone structure of the early 19th century, measuring 1534 ft. in length, and by a railway bridge connecting the station of the Orleans railway company in La Bastide with that of the Southern company on the left bank. Looking west from the Pont de Bordeaux, the view embraces a crescent of wide and busy quays with a background of lofty warehouses, factories and mansions, behind which rise towers and steeples. Almost at the centre of the line of quays is the Place des Quinconces, round which lie the narrow, winding streets in which the life of the city is concentrated. Outside this quarter, which contains most of the important buildings, the streets are narrow and quiet and bordered by the low white houses which at Bordeaux take the place of the high tenements characteristic of other large French towns. The whole city is surrounded by a semicircle of boulevards, beyond which lie the suburbs of Le Bouscat, Cauderan, Merignac, Talence and Begles. The principal promenades are situated close together near the centre of the city. They comprise the beautiful public garden, the allees de Tourny and the Place des Quinconces. The latter is planted with plane trees, among which stand two huge statues of Montaigne and Montesquieu, and terminates upon the quays with two rostral columns which serve as lighthouses. On its west side there is a monument to the Girondin deputies proscribed under the convention in 1793. At its south-west corner the Place des Quinconces opens into the Place de la Comedie, which contains the Grand Theatre (18th century), the masterpiece of the architect Victor Louis. The Place de la Comedie, the centre of business in Bordeaux, is traversed by a street which, under the names of Cours du Chapeau-Rouge, rue de l'Intendance and rue Judaique, runs from the Place de la Bourse and the quai de la Douane on the east to the outer boulevards on the west. Another important thoroughfare, the rue Sainte Catherine, runs at right angles to the rue de l'Intendance and enters the Place de la Comedie on the south. The Pont de Bordeaux is continued by the Cours Victor Hugo, a curved street crossing the rue Sainte Catherine and leading to the cathedral of St Andre. This church, dating from the 11th to the 14th centuries, is a building in the Gothic style with certain Romanesque features, chief among which are the arches in the nave. It consists of a large nave without aisles, a transept at the extremities of which are the main entrances, and a choir, flanked by double aisles and chapels and containing many works of art. Both the north and south facades are richly decorated with sculpture and statuary. Of the four towers flanking the principal portals, only those to the north are surmounted by spires. Near the choir stands an isolated tower. It contains the great bell of the cathedral and is known as the Clocher Pey-Berland, after the archbishop of Bordeaux who erected it in the 15th century. Of the numerous other churches of Bordeaux the most notable are St Seurin (11th to the 15th centuries), with a finely sculptured southern portal; Ste Croix (12th and 13th centuries), remarkable for its Romanesque facade; and St Michel, a fine Gothic building of the 15th and 16th centuries. The bell tower of St Michel, which has the highest spire (354 ft.) in the south of France, dates from the end of the 15th century, and, like that of the cathedral, stands apart from its church. The palace of the Faculties of Science and of Letters (1881-1886) contains the tomb of Michel de Montaigne. The prefecture, the hotel de ville, the bourse and the custom-house belong to the 15th century. The law-courts and the hospital of St Andre (the foundation of which dates from 1390) belong to the first half of the 19th century. Of greater antiquarian interest is the Palais Gallien, situated near the public garden, consisting of remains of lofty arcades, vaulting and fragments of wall, which once formed part of a Roman amphitheatre. Bordeaux lost its fortifications in the 18th century, but four of the old gateways or triumphal arches belonging to that period still remain. Still older are the Porte de Cailhau, once the entrance to the Palais de l'Ombriere, which before its destruction was the residence of the duke of Aquitaine, and the Porte de l'Hotel de Ville, the former of the 15th, the latter of the 13th and 16th centuries.

Bordeaux is the seat of an archbishop, the headquarters of the XVIII. army corps, the centre of an _academie_ (educational division) and the seat of a court of appeal. A court of assizes is held there, and there are tribunals of first instance and of commerce, a council of trade-arbitrators, a chamber of commerce and a branch of the Bank of France. Its educational institutions include faculties of law, of science, of letters and of medicine and pharmacy, a faculty of Catholic theology, lycees, training colleges, a higher school of commerce, a chair of agriculture, a school of fine art and a naval school of medicine. There are several museums, including one with a large collection of pictures and sculptures, a library with over 200,000 volumes and numerous learned societies.