BOIIACIC ACID BORDELAIS. 



627 



it communicates a green colour. It contains 43 per 

 cent, of water, which it parts with, on being heated 

 to redness, when it melts into a transparent glass, 

 and is called calcined boracic acid. 



Boracic acid was discovered by Sir H. Davy to be 

 a compound of a peculiar base, which he called boron, 

 and oxygen, in the proportion of eight parts of the 

 former to sixteen of the latter. Its principles are 

 separated both by means of galvanism and by the 

 action of potassium. Boron is a tasteless and inodo- 

 rous substance, in the form of a greenish-brown 

 powder. It is insoluble in water, ether, alcohol, and 

 oils ; nor does it fuse when subjected to the strongest 

 heats. By exposure to common air, it gradually be- 

 comes oxygenated, and, when heated in oxygen gas, 

 bums vividly, and is converted into boracic acid. 



Boracic acid is sometimes employed in the analysis 

 of minerals, and for soldering metals in the arts ; and, 

 since its discovery in such abundance in the Italian 

 springs and lakes, it lias also been used in the manu- 

 facture of borax, being united with soda. 



The most important combination formed by boracic 

 acid is that with soda, commonly called borax. It is 

 brought into Europe, in an impure state, from the 

 East Indies, under the name of tincal, and is under- 

 stood to occur principally in certain lakes, from 

 whence it is obtained by evaporation. It is also re- 

 ported to be dug from the, earth in Thibet, and to 

 exist in the mines of Riquintipa arid Escapa, in South 

 America. A knowledge of its manufacture was, for 

 a long time, confined to the Venetians and Hollan- 

 ders. This is now known to consist in boiling car- 

 bonate of soda with the calcined tincal, in order to 

 saturate its excess of acid : twelve pounds of carbo- 

 nate of soda are requisite for every hundred pounds 

 of washed tincal, in the water : the lie is left to cool 

 gradually and crystallize. The French nation manu- 

 facture their borax (of which they consume about 

 twenty-five tons annually) from the boracic acid found 

 in the Italian lakes ; in consequence of which the 

 price of this article has fallen in France from five 

 shillings and ten pence the pound, to two shillings 

 Hiid two pence. The process which they adopt is to 

 dissolve 1200 pounds of carbonate of soda in 1000 

 pounds of water, to which is added, by 20 pounds 

 at a time, 600 pounds of Tuscan boracic acid. This 

 is done in a leaden boiler, of double the capacity re- 

 quisite to contain the materials, in order to provide 

 for the effervescence which takes place. The heat 

 is kept up for thirty hours, when the clear liquid is 

 drawn off into leaden coolers, a foot in depth, where 

 the first crop of crystals deposits itself in three days. 

 A hundred pounds of the best Tuscan boracic acid 

 produce about a hundred and fifty of borax. 



Borax appears in crystalline masses of a moderate 

 size, or in distinct hexagonal prisms, terminated by 

 three or six-sided pyramids ; is of a white colour, 

 and transparent. It requires twenty parts of cold* 

 and six of boiling water for its solution. Exposed to 

 heat, it swells up, boils, loses its water of crystalliza- 

 tion, and becomes converted into a porous, white, 

 opaque mass, commonly called calcined borax. A 

 stronger heat brings it to the form of a vitreous 

 transparent substance, in which state it is known 

 under the name of glass of borax. Borax forms one 

 of the best fluxes known. It is used in the analysis 

 of minerals by the blow-pipe, in melting the precious 

 metals, in forming artificial gems, and in soldering. 



Another native combination of boracic acid is that 

 with magnesia, known, in mineralogy, under the 

 name of boracite. It is found in small crystals, im- 

 bedded in gypsum, near Lunenburg, in Lower Sax- 

 ony, and at Segeborg, in Holstein. Their form is 

 that of a cube, with the edges and four of the solid 

 angles truncated. They are remarkable for their 



electric properties, becoming, when heated, nega- 

 tively electrified at their perfect angles, and positive- 

 ly so at their truncated angles. 



BORAK AL. See Alborak. 



BORDA, Jean Charles, an engineer, and afterwards 

 a captain in the French marine, famous for his ma- 

 thematical talents, was born at Dax, in the depart- 

 ment of Landes, in 1733. In 1756, he was chosen a 

 member of the academy of sciences, and occupied 

 himself in making experiments on the resistance of 

 fluids, the velocity of motion, and other topics relating 

 to dynamical science. In 1767, he published a dis- 

 sertation on hydraulic wheels, and afterwards one on 

 the construction of hydraulic machinery. In 1771, 

 with Verdune and Pingre, he made a voyage to 

 America, to determine the longitude and latitude of 

 several coasts, isles, and shoals, and to try the utility 

 of several astronomical instruments. In 1774, he 

 visited the Azores, the cape Verde islands, and the 

 coast of Africa, for the same purpose. In the Ame- 

 rican war, he was very useful to the count d'Estaing, 

 by his knowledge of navigation. In later times, he 

 visited a second time the Azores, the cape Verde 

 islands, and the coast of Africa ; but the observations 

 which he made in this voyage have not been pub- 

 lished. B. was the founder of the schools of naval 

 architecture in France. He invented an instrument', 

 of a very small diameter, which measures angles 

 with the greatest accuracy, and which has been usrd 

 in measuring the meridian ; the reflecting circle, 

 which has made his name immortal ; besides an in- 

 strument for measuring the inclination of the compass 

 needle, and many others. On the establishment of 

 the national institute, he became one of its members, 

 and was occupied, with other men of science, in 

 framing' the new system of weights and measures 

 adopted in France under the republican government. 

 Among the latest of his labours was a series of ex- 

 periments to discover the length of a pendulum 

 which should vibrate seconds, in the latitude of Paris. 

 Among his writings are Recherches sur la Resistance 

 des Fluides ; Nouvelle Methode pour observer la Lon- 

 gueur du Pendule ; Nouveau Systeme do Poids el 

 Mesures, adopte par les Etats Generaux, &c. The 

 principal are. his Voyage, published in 2 vols. in 

 1778, and his Tables Trigonometriques Decimates, 

 which have been edited by Delambre. He died at 

 Paris, in 1799. 



BORDEAUX. See Bourdeaux. 



BORDELAIS WINES. The finer red wines of the 

 Bordelais (country round Bourdeaux) are the best 

 which France produces. They contain but little al- 

 cohol, keep well, and even improve by removal. As 

 the original fermentation is complete, they are, if 

 judiciously managed, less subject to disorder and 

 acidity than the Burgundy wines. None of the very 

 best quality, however, is exported pure ; a bottle of 

 the best Chateaux- Margaux, or Haut-Brion, is a 

 rarity hardly to be procured in Bourdeaux itself, at 

 the rate of six or seven franks a bottle. For export, 

 the secondary growths of Medoc are mingled with 

 the rough Palus. The red wines of the Bordelais 

 are known in England and North America under the 

 name of claret. They have less aroma and spirit, 

 but more astringency, than the Burgundy wines. 

 The Bordelais are the safest wines for daily use, as 

 they are among the most perfect of the light wines, 

 and do not easily excite intoxication. They have 

 been accused of producing the gout, but without 

 reason. Persons who drench themselves with Ma. 

 deira, Port, &c., and indulge in an occasional debaucl' 

 of claret, may, indeed, be visited in that way ; be- 

 cause a transition from the strong brandied wines to 

 the lighter is always followed by a derangement of 

 the digestive organs. 



