However expressed, the compound is generally regarded by the best authorities as consisting of 1 equivalent of chlorine, 1 of calcium, and 1 of oxygen. Theoretically it should afford 48.96 per cent. of chlorine; but by reason of its liability to decompose, the chlorine in the commercial article averages only from 30 to 33, and rarely exceeds 36 per cent.; indeed, after being kept a few months, it is oftener found to contain less than 10 per cent. of available chlorine. Its value depending upon the quantity of chlorine, that is readily evolved, and as by exposure portions of the chlorine become fixed by new combinations of chloride of calcium and chlorate of lime, the methods of testing bleaching powder are dependent, not on the absolute quantity of chlorine present, but on that easily displaced. The operation of thus testing its value is termed chlorimetry. One process, in common use by the bleachers, is in determining the quantity of indigo of which a certain amount of the powder will destroy the color. The accuracy of this operation, however, cannot be relied upon, the indigo not being of uniform quality, and its solution being subject to decomposition by keeping. The simplest and most accurate test is the determination of the quantity of sulphate of iron, which, when in solution, is converted, through the influence of the chlorine evolved, into the sesquioxide of iron. The change is known to be completed when a dingy green is given to the liquid on addition of ferricyanide of potassium. This test, as adopted by the U. S. Pharmacopoeia of 1850, is thus applied: "When 40 grains of the powder triturated with a fluid ounce of distilled water are well shaken with a solution of 78 grains of crystallized sulphate of protoxide of iron and 10 drops of sulphuric acid, in 2 fluid ounces of distilled water, a liquid is formed, which does not yield a blue precipitate with ferricyanide of potassium (red prussiate of potash)." If the powder contain less chlorine than the proportion required by the Pharmacopoeia (25 per cent.), the protoxide will not be all converted into the sesquioxide, and the precipitate with the prussiate of potash will be of blue color.-Beside its use for bleaching purposes, chloride of lime, or chlorinated lime, as it is also called, is employed in medicine as a disinfectant and desiccant. It is applied as a wash for ulcers, burns, cutaneous eruptions, &c.; a gargle for putrid sore throat; and is administered internally in typhoid fever, scrofula, and other diseases. By the facility with which it is made to give up its chlorine, it is a very valuable agent for disinfecting all places exposed to noxious effluvia. It is applied to purify the air of hospitals, ships, &c., and is believed to be influential in preventing the spread of contagion by destroying the pestilential miasma. Animal and vegetable decompositions are checked; and it is thus made useful as an antiseptic. In long voyages it is applied to the purification of the water used on board

ships. One or two ounces are put in a hogshead of water, and after exposure to the air and settling, the quality of this is found to be much improved.

BLEAN, a parish in the county of Kent, England, and the centre of a poor-law union comprising 16 parishes. The forest of Blean was anciently of vast extent, and even as late as the time of Henry VI. it was the scene of wild boar hunts. It has now lost its privileges. Pop. about 600.

BLEDSOE, a S. E. county of Tennessee, comprising an area of 480 sq. m., and drained by Sequatchie river. It has an uneven and partly mountainous surface, and in 1850 produced 407,025 bushels of corn, 83,670 of oats, and 42,427 pounds of butter. There were 23 churches, and 600 pupils attending public schools. Mineral coal is found in several parts of the county. Capital, Pikeville; pop. 5,959, of whom 827 were slaves.

BLEECKER, ANN ELIZA, an American poetess, was the youngest daughter of Mr. Brandt Schuyler, born in New York, in Oct., 1752, died at Tomhanick, above Albany, Nov. 23, 1783. She married, in 1769, Mr. John J. Bleecker, lived with him one year at Poughkeepsie, then removed to Tomhanick, whence she was driven by the news of the approach of Burgoyne's army. Her husband had already left to provide means of escape, when she was obliged to fly on foot, in the midst of her family, and of a crowd of other helpless persons, for refuge from the advancing savages. After enduring great horrors and distresses, they made their escape to Albany, and thence by water to Red Hook, where they remained until the surrender of Burgoyne enabled them to return to their home. In 1781, her husband was captured, with two of his laborers, while working in a field, and carried off toward Canada, but intercepted by a party from Bennington. She visited New York in the spring of 1783, but found the changes of time and war oppressive to her sensitive mind. Her poems were written as suggested by occasions, without a view to publication. She possessed a sportive fancy, with much tenderness of feeling, but the sad experiences of her life produced upon her such an effect, that she destroyed "all the pieces that were not as melancholy as herself." Her poems are to be found in the earlier numbers of the "New York Magazine," and a collection of her stories and "poetics" in a volume published in 1793, by her daughter Margaretta.

BLEGNO, or BLENJO, also BRENNO, a river of Switzerland, flowing into the Ticino (or Tessin), near Biasca. A fertile district of the canton of Ticino, called the Val-di-Blegno, derives its name from this river.

BLEMMYES, a nomadic tribe of Ethiopia, fabled to have been without heads, their eyes and mouths being placed in their breast.

BLENDE (Germ. blenden, to dazzle), a common ore of zinc, the sulphuret, composed of sulphur 33, zinc 67; often found in shining crystals, whence

its name. It is of resinous or adamantine lustre; of yellow, brown, black, and rarely red, green, and white colors; of hardness 3.5 to 4, and specific gravity 4.063. It accompanies galena, the common ore of lead, and is found in numerous localities, in the metamorphic rocks and the secondary limestones and sandstones through out the country. Though so abundant, and so rich in metal, it is found difficult of reduction, and no use is made of it in this country. The English employ it to some extent, and its price has been about $15 per ton, half the value of calamine, the silicate of zinc, which is not quite so rich an ore. The Chinese reduce the sulphuret successfully.

BLENHEIM, or BLINDHEIM, a village about 23 miles from Augsburg, in Bavaria, the theatre of a great battle, fought Aug. 13, 1704, between the English and Austrians, under Marlborough and Prince Eugene, and the French and Bavarians, under Marshal Tallard, Marsin, and the elector of Bavaria. The Austrian states being menaced by a direct invasion on the side of Germany, Marlborough marched from Flanders to their assistance. The allies agreed to act on the defensive in Italy, the Netherlands, and the lower Rhine, and to concentrate all their available forces on the Danube. Marlborough, after storming the Bavarian intrenchments on the Schellenberg, passed the Danube, and effected his junction with Eugene, after which both at once marched to attack the enemy. They found him behind the Nebel brook, with the villages of Blenheim and Kitzingen strongly occupied in front of either flank. The French had the right wing, the Bavarians held the left. Their line was nearly 5 miles in extent, each army having its cavalry on its wings, so that a portion of the centre was held by both French and Bavarian cavalry. The position had not yet been properly occupied according to the then prevailing rules of tactics. The mass of the French infantry, 27 battalions, was crammed together in Blenheim, consequently in a position completely helpless for troops organized as they were then, and adapted for line fighting in an open country only. The attack of the Anglo-Austrians, however, surprised them in this dangerous condition, and Marlborough very soon drew all the advantages from it which the occasion offered. Having in vain attacked Blenheim, he suddenly drew his main strength toward his centre, and with it broke through the centre of his opponents. Eugene made light work of the thus isolated Bavarians, and undertook the general pursuit, while Marlborough, having completely cut off the retreat of the 18,000 Frenchmen blocked up in Blenheim, compelled them to lay down their arms. Among them was Marshal Tallard. The total loss of the Franco-Bavarians was 30,000 killed, wounded, and prisoners; that of the victors, about 11,000 men. The battle decided the campaign, Bavaria fell into the hands of the Austrians, and the prestige of Louis XIV. was gone. This battle is one of the highest

tactical interest, showing very conspicuously the immense difference between the tactics of that time and those of our day. The very circumstance which would now be considered one of the greatest advantages of a defensive position, viz., the having 2 villages in front of the flanks, was with troops of the 18th century the cause of defeat. At that time, infantry was totally unfit for that skirmishing and apparently irregular fighting which now makes a village of masonry houses, occupied by good troops, almost impregnable. This battle is called in France, and on the continent generally, the battle of Hochstädt, from a little town of this name in the vicinity, which was already known to fame by a battle fought there on Sept. 20 of the preceding year.

BLENNERHASSET, HARMAN, the most noted victim of Aaron Burr's conspiracy, born in Hampshire, England, about 1769, died in the island of Guernsey, in 1831. He was of Irish descent. He was called to the Irish bar, but becoming discontented with the position of Ireland, and indulging no hopes of her emancipation, he resolved on emigrating to America. He married Miss Adeline Agnew, a lady of remarkable beauty and accomplishments, sold his Irish estates, and sailed for New York in 1797. There he remained for several months, engaged in studying the topography of the New World, and, at length, attracted by what he heard of the region of Ohio, then almost a wilderness, he resolved on emigrating thither. He was a man of handsome fortune, and of romantic tastes; and in the spring of 1798, having spent the previous winter at Marietta, he purchased a small island in the Ohio river, called Backus Island, about 2 miles below Parkersburg. This spot of 170 acres he proceeded to clear, and call after his own name; and he then erected on it a noble mansion, which he filled with rich furniture, while the grounds were elaborately cultivated and adorned. In the course of a few years, Blennerhasset spent not less than $60,000 in embellishments; and being a man of letters, of elegant manners, and genial tastes, his home became one of the most attractive places in the American states. The stranger who was so fortunate as to be properly introduced, found, to his surprise, that amid the rugged wilds of Ohio, he was surrounded by comforts and elegance. He discovered in his hostess one whose commanding beauty of person was enhanced by the charms of elegant culture. In the husband he saw the man of refined mind, surrounded by books and philosophical apparatus, who had voluntarily sought his romantic seclusion. In 1805, during Blennerhasset's absence from home, Burr came to the island in company with a female companion, ostensibly to gratify his curiosity. Mrs. Blennerhasset discovering who he was, invited him into the house, and an acquaintance was thus commenced. At this time Burr was fully resolved upon his Mexican schemes; and as Blennerhasset was then regarded as one of the most prominent char

acters in the western country, he resolved to gain his confidence, and induce him to embark in his enterprise. In December, 1805, Burr addressed an insinuating letter to Blennerhasset, regretting not having made his acquaintance, flattering him with hints of his talents and adaptation for public affairs, and urging him again to take an active part in life. He held out inducements that his time might be advantageously occupied, and his fortune increased, to which Blennerhasset, who now found his property gradually diminishing, gave too ready a hearing. Burr's letter was soon answered, Blennerhasset, who imagined the country to be on the eve of a war with Spain, expressing a desire to engage in any enterprise which promised sufficient reward. In August, 1806, Burr again visited the island. In a short time, both Blennerhasset and his wife were fully committed. Blennerhasset now largely invested his means in boats, provisions, arms, and ammunition. He left his home and family and went to Kentucky, where being warned of Burr's real designs, he returned to the island greatly disheartened. However, through Burr's repeated solicitations, and the persuasions of his wife, who had now enlisted in the undertaking with her whole soul, he persisted. A proclamation against the scheme having been published by President Jefferson, Blennerhasset, who was in hourly expectation of being arrested by Col. Phelps of Parkersburg, escaped from the island Dec. 10, in company with a Captain Comfort Tyler, and managing to elude pursuit joined Burr's flotilla at the mouth of the Cumberland river. Col. Phelps's party arrived at the island to find it deserted, and while their commander was temporarily absent at Point Pleasant, in an ineffectual attempt to arrest Blennerhasset, the men committed the most wanton outrages, burning the fences, destroying the shrubbery, and hacking the furniture. Mrs. Blennerhasset bore her part during all these trying scenes with great composure, and at length in the dead of winter set out in a wretched boat to join her husband. She was disappointed in not seeing him at the mouth of the Cumberland, but on the Mississippi at the entrance of Bayou Pierre she with her children was restored to him.-Burr's scheme resulting in total failure, he surrendered himself to the United States authorities. Blennerhasset having been arrested was discharged, and imagining that he had nothing more to fear from the government, left Natchez in June, 1807, with the intention of revisiting his island and fully examining into his shattered fortunes. On his way he stopped at Lexington, Ky., and while there was arrested and thrown into prison. Having secured the legal services of Henry Clay, he endeavored to procure his discharge by the court. But this was not granted, and he was forced to proceed to Richmond, under guard, to take his trial for treason. Burr, tried upon 2 indictments, was declared not guilty; and those against the other conspirators were never prosecuted. Bankrupt in fortune, and

broken down in mind, Blennerhasset returned to Natchez. His island had been seized by creditors, every thing upon it which could be converted into money had been sold at ruinous sacrifice, and the beautiful grounds were used for the culture of hemp. Coming into possession of a sum of money, by what means it is not certainly known, he now bought 1,000 acres of land near Gibson's Port, Mississippi, for a cotton plantation; but the war of 1812 prostrated all commercial enterprises. While settled at this place, he heard of the destruction of his former home at the island by fire, the house, used as a store-house for hemp, having accidentally been fired by some careless negroes. Becoming continually poorer, in 1819 he removed with his family to Montreal, but there again was disappointed. sailed for Ireland in 1822, to prosecute a reversionary claim still existing there. In this he failed; nor did he meet with any success in his application for aid to the marquis of Anglesey, whom he had formerly known. In 1842, Mrs. Blennerhasset returned to America, and memorialized congress for a grant of money for the spoliation of her former home. The petition would doubtless have been successful, but before it could be acted upon, she died in New York in most abject poverty, and was buried by strangers.

He

BLERE, a town in France, department of Indre-et-Loire; pop. in 1856, 3,676. In the vicinity stands the castle of Chenonceaux, one of the most interesting objects in this part of France. Originally a simple manor house, it was enlarged during the reign of Francis I. to its present dimensions. Henry II. purchased it in 1535, and bestowed it, together with the duchy of Valentinois, on the celebrated Diana of Poitiers, who, before completing the magnificent embellishments which she had commenced, was forced to yield it to her rival, Catharine de' Medici. The latter adorned the castle still more richly than her predecessor, and surrounded it with a beautiful park. It afterward came into the possession of the house of Condé, and after many vicissitudes was purchased in 1733 by Gen. Dupin, a gentleman distinguished less perhaps by his own learning than by the wit and beauty of his wife. Graced with the accomplishments of Madame Dupin, Chenonceaux became the resort of some of the most celebrated men of the 18th century. Montesquieu, Buffon, Voltaire, Fontenelle, Bolingbroke, and others, were among its frequent visitors. The castle is built on a kind of bridge across the Cher, and has a long gallery reaching from one side of the river to the other. The architecture, furniture, and decorations are all of the time of the Valois. It is still in excellent preservation.

BLESSING. See BENEDICTION.

BLESSINGTON, MARGARET, countess of, an Irish literary lady, chiefly celebrated for her popular social qualities and her brilliant receptions at Gore House, born Sept. 1, 1789, at Car

1806 he was made governor of New South Wales, and acted there in such an arbitrary manner that his colleagues, civil and military, agreed to arrest him, and he was sent back to England in Jan. 1808. The home government justified the action and condemned Bligh. This circumstance has led people to believe that Bligh's conduct on the quarter-deck was despotic and inhuman.

BLIGHT, a popular name for various distempers incident to cultivated plants. It may be occasioned by insects either at the roots or in the branches, by cold winds and frosty nights in the spring, or by the ravages of parasitical fungi. It makes the leaves wither, curl up, turn yellow, or fall off, and if not remedied causes the destruction of the plant.

BLIND, THE, persons who have either lost, or never possessed, the power of vision. Blindness may be either complete or incomplete. It is complete when there is no consciousness of light, and no ability to discern even the dim form of large objects. It occurs in amaurosis, and in all those cases which are the result of destruction of the ball of the eye. In incomplete blindness, there is a consciousness of light which enables the person to distinguish between day and night, and to discern imperfectly the outline of objects of considerable size. There is a class in most of the institutions for the instruction of the blind called "seeing blind," who are capable of distinguishing objects by some exertion, and who, in consequence of this imperfect vision, are doubly unfortunate, lacking the high cultivation of the other senses so commonly attained by the blind, and yet not possessing sufficient vision to be of much service to them. Yet despite this difficulty, some of them have attained to very considerable distinction. The blindness of the celebrated American preacher and lecturer, Rev. W. H. Milburn, is of this description. Blindness, though congenital in many instances, is less frequently so than deafness. When congenital, its causes are generally analogous to those which induce idiocy, deafness, and insanity. Intermarriage of near relations, scrofula or other diseases of parents, and intemperance on the part of parents, are very common causes. There are many cases, however, which cannot be thus accounted for. Blindness occurring subsequent to birth, is usually the result of purulent ophthalmia, conjunctivitis, iritis, cataract, amaurosis or gutta serena, small-pox, scarlet fever, measles, or accident, from powder, blows on the eye, &c. Of the diseases enumerated, purulent ophthalmia and amaurosis are most fatal to sight. The latter, which consists in paralysis of the optic nerve, is very seldom cured. It was the cause of Milton's blindness. Aged persons frequently become blind from the inability of the lachrymal glands to secrete tears sufficient to lubricate the eye, from absorption of the aqueous humor, opacity of the cornea or lens, &c. Iritis is emphatically a disease of cities, being, except in cases of accident, which are rare, almost invariably one of

the results of syphilitic disease. Persons affected with congenital blindness, and who consequently have no idea of vision, have occasionally been restored to sight by surgical operations, but in most cases the result has been such a confusion of ideas as to make vision of little service for a long time. In a case related by Cheselden, a young man born blind, but whose sight had been restored by an operation, was unable to determine the distance of objects from him by sight, and 7 years after the operation, was accustomed to close his eyes when. ever he wished to ascertain their proximity. The diseases of the eye have of late years received much attention, and eminent men have made their treatment a speciality. Most of our large cities have hospitals or infirmaries devoted to the treatment of these diseases, and Jones, Lawrence, Mackenzie, Hays, and others, have published elaborate treatises on the subject. The operation for the cure of strabismus or squinting, which some years ago was very common, is much less resorted to at the present day than formerly. The operations for cataract, which is an opacity of the crystalline lens (couching, or depressing, and dividing the lens to remove it from the field of vision) have resulted in the partial restoration to sight of many blind persons.-The statistics of blindness in different countries reveal some singular facts. As we proceed toward the equator, the proportion of the blind to the entire population increases with great rapidity, and the same fact is observable in the very high latitudes. M. Zeune, the late accomplished director of the institute for the blind at Berlin, some years ago prepared a table on the subject, which subsequent observations on the eastern continent have very nearly verified. The following were the results at which he arrived:

Between 20 and 30 N. lat. the ratio of the blind

to the inhabitants is..

66

1 to 100

1 to 300

The white glittering sand, and the intense heat of the sun, shining always from a clear sky in Egypt and northern Africa, cause diseases of the eye, and especially ophthalmia, to be very prevalent in those regions, and similar causes prevail, though to a less extent, in southern Europe. Among the densely populated nations of central Europe accidents with gunpowder, small-pox, and other epidemic diseases, are the most frequent causes of destruction of sight. In the temperate regions of the north the number of the blind is comparatively small, but as we approach the arctic circle, the glittering snows, the smoky dwellings, the alternation from the brilliant nights of the arctic summer to the deep darkness of the arctic winter, all exert their influence upon the visual organs. On this side of the Atlantic, however, a different ratio seems to prevail. We have not the means for an accurate comparison, except of