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gravity of the unloaded beam, the graduation must <ommence from that point, because when the loop of the movable fulerum is there, it poises the unloaded beam. By suspending from the hook at w, 1, 2, 3, &c. lbs. in succession, the divisions may be found to which the fulerum must be removed in order to produce equilibrinm, and the weight of the substance in the scale pan is indicated by the number of the point at which the fulerum is placed when the instrument is in equilibrinm.

The bent lecer balance is made in a variety of forms, the principle of which will be understood from a common form shown in Fig. 91. It consists of a bent lever A B C, movable about an axis B. To one end of the lever, a constant weight c is fixed, and to the other end A, a hook with a scale-pan A attached, for containing the substance to be weighed. Through the centre of motion B, draw a horizontal line Abd, upon which, from A and c let fall perpendiculars; then if B A and B D are reciprocally proportional to the weights at A and c, they will be in equilibrio; but if not, the weight c will move upwards or downwards along the arc till that ratio is obtained. As the weight in w depresses the shorter arm B A, its leverage is constantly diminished, while that of the arm c B is constantly increased. When c counterpoises the weight, the division at which it settles on the graduated arc expresses its amount. The graduation, of course, commences at the point at which the index settles when there is no load in w.

[See also Weighing Machines, Weights and Measures, and Watch.]

BALCONY. (Italian, balco or palco; French, balcon) An open gallery projecting from the front of a building, and surrounded by a rail or balustrade of various devices, and supported by cantalivers, brackets or columns. A baleony may be constructed of wood, iron, or stone. Cast-iron is sometimes used, and at other times bar-iron fashioned into crail work of various figures. Baleonies are generally made on a level with the sills of the windows of the first floor, and the windows are generally brought down to the floor. Sometimes a portico or poreh is surmounted with a baleony, in which case the balustrade may be of stone, iron, or wood.

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BALLAST. (Anglo-Saxon, be-hlastan, to lade a ship.) The heavy materials, stone, gravel or iron, placed in the hold of a ship, in order to make the centre of gravity correspond with the trim and shape of the vessel, so as to be neither too high nor too low; neither too far forwards nor too far aft. The object is to lade the ship so deep that the surface of the water may rise nearly to the extreme breadth amidships. She will thus be able to carry a good sail, incline but little, and ply well to the windward. Iron ballast is alone used in the Royal Navy, but in merchantmen it is of various kinds, and masters are obliged to declare the quantity they bear, and to discharge it at certain places. Many excellent ports have been ruined by ballast being discharged in havens, roadsteads, &c. A ship is said to be in ballast when it has no other loading. For the regulations respecting ballast the reader is referred to McCulloch's Dictionary of Commeree, 1850.

BALLISTIC PENDULUM. [See Pendulum.]

BALLOON. [See Aerostation.]

BALSAMS. The juices of certain trees and shrubs, capable of being applied to useful purposes in medicine and the arts. Balsams contain in general benzoic or cinnamic acid, with a volatile oil, and resins of variable consistency. They consequently vary in substance, thickening by degrees, and sometimes becoming entirely solid. The term balsam is by some writers confined to those juices which contain benzoic acid with a volatile oil and resin; while such as contain only resin and volatile oil are called turpentines or oleo-resins. This would exclude the balsams of Gilead, Copaiba, &c., in which there is no benzoic acid; but in ordinary language these continue to be ranked among the true balsams, the principal of which are the balsams of Peru and Tolu, benzoin, storax, and liquidamber. Peru balsam is obtained from a branching elegant tree (Myrospcrmum Peruiferum), growing in Peru, New Granada, &c., and is imported in two states, one called white, the other black. The former is the spontaneous exudation from the tree, the latter the result of boiling the bark and branches. The black balsam is the ordinary form. It is imported from Valparaiso in canisters or earthen pots, is of the consistence of treacle, and on account of its high price is extensively adulterated with turpentine, copaiba, or volatile oil. 1,000 parts genuine black balsam ought to saturate 75 parts pure carbonate of potash. Black balsam is fragrant, and is therefore employed as a perfume for pomatums, sealing-wax, lozenges, &c., and occasionally for chocolate and liqueurs. Balsam of Tolu is obtained from a closely allied species of tree, if not from the same species as that which yields Peru balsam. It has the taste and odour of the white balsam of Peru, and its constituents are the same. These balsams scareely differ, except that in Tolu there is a facility of becoming resinified, which does not exist in the other.

Benzoin, improperly called a gum, and known as Gum Benjamin, must rank among balsams and resins. It is quite insoluble in water, and is the hardened and fragrant juice of a tree (Styrax benzoin, or Lithocarpus benzoin) growing in Sumatra, Borneo, &c. Iu commerce it is met with in cakes, the best of which are of a light yellowish or fawn-colour, with portions of an almond shape, whiter than the rest. This is from the younger trees, and is called Benzoe amygdaloides. The chief use of benzoin is in yielding benzoic acid, but it is also much employed in perfumery, and helps to give the peculiar fragrance to the incense burnt in Roman Catholic censers. It is likewise an ingredient in varnishes, for such articles as are liable to be much handled, its fragrance being evolved by the beat of the hand. For the same reason it is added to the spirituous solution of isinglass, of which court-plaster is made.

Storax belongs to the same natural family as benzoin, being the product of Styrax officinalis, a handsome shrub, a native of Syria, Italy, and most parts of the Levant, and common all over Greece and the Peloponnesus. The storax of commerce is obtained from Asiatic Turkey. It is procured by incisions in the bark of the tree, whence oozes a liquid resinous substance which hardens in tears about the size of peas, and these in masses, constitute the rare and valued Styrax albus. Various qualities are met with in commerce, but the ordinary kinds are largely adulterated with saw-dust and resin. Storax was formerly imported wrapped in a leaf Tinder the name of reed or cane styrax, (Styrax calamita,) but the substance now so called is a black or brown article in powder or in grains, or in agglutinated lumps. Another kind common in the drug market is called liquid storax, and is a darkcoloured substance with a disagreeable odour, more resembling coal-tar than balsam. For medical purposes it is necessary to purify storax in aleohol, and distil before the balsam is used. There is another substance called Storax in commerce which is often confounded with this; but is the product of the Liquidamber styraciflua, belonging to the natural family Balsamacea. This fine tree grows in Mexico and the United States, and resembles our lesser maple. A fragrant resin exndes, but not very copiously, from incisions in the stem, and this becoming dry and opaque forms the soft or white liquidamber.

Among balsams or oleo-resins in which there is an absence of benzoic acid are the following. Copaiba or Copaiva Balsam obtained from various species of Copaifera, trees growing in South America. The balsam flows freely from the stem as a clear transparent liquid like olive-oil, but thickens afterwards. From it are prepared essential oil of copaiba, resin of copaiba, and copaivic acid, employed in medicine. The balsam is also used for making paper transparent, and for certain kinds of lacquering. Mecca Balsam is the produce of a shrub (Amyris Gileadensis) growing at Gilead in Jndea. It is turbid when fresh, but becomes clear and transparent by degrees. Chinese varnish and Japan lac varnish, whose names betoken their origin, are both valuable varnishes. The former is soluble in aleohol and ether, the latter in oil.

Vol. r.

BALUSTRADE. (Latin balustrum, a space in the ancient baths that was railed in.) A range of small columns or balusters supporting a cornice and used as a parapet or a screen to conceal the whole or a part of the roof. Balustrades are also employed on the margins of stairs, or before windows, or to inclose terraces or baleonies by way of security; or to separate one place from another, as around altars, fonts, or on the sides of the passage way of bridges. The word is sometimes improperly spelt banister.

BANDANAS. [See Calico Printing.]

BARBERRY. (Berberis.) A family of plants bearing acid fruit, and giving its name to the natural order Berberidacea. The common barberry is a graceful shrub, well known in England as well as in most temperate climates. De Candolle speaks of it as extending from Candia to Christiana; but neither this species nor any other of the family has been met with in Africa, Australia, or the South Sea Islands. In northern latitndes the barberry affects the valleys, in southern the mountains; it is found on Mount JEtna at the height of 7,500 feet. In North and South America it is well known, and has been observed far south, near the straits of Magellan.

The fruit of this shrub is a cluster of drooping berries, of a beautiful coral red. Owing to the oxalic acid they contain, these berries are very sour, but they form with sugar an agreeable preserve, for sweetmeats, tarts, &c., and an excellent jelly. A cooling drink is made from them for invalids, and they are also pickled with vinegar, as a garnish for dishes. But it is on account of the yellow colouring matter and astringent properties of the stem and bark that the barberry has a place in our pages, for these make it useful as a dyeing material. The root is also bitter and styptic, and is used in Poland to give a yellow colour to leather. Anlndian species (Berberis tinclorid) has a similar reputation for yielding a good yellow colouring material, and also furnishes a decoction which is said to give relief in cases of ophthalmia. The colouring matter is found in the whole of the root, but in the stem it is only deposited round the pith and near the bark; the great bulk of the woody fibre contains no colour. As the natives of India are skilful in making extracts, it has been suggested, that the colouring matter be sent to England in that form, and without the additional weight of the woody fibre. The colour is quite as good as that of the European root which we import from Cologne and Hamburg. Siberian barberry is known among the Mongol Tartars as Yellow-wood, and is applied by them to superstitious as well as medicinal uses. There are several varieties of the common barberry, differing but little in general character, but varying in the appearance of the fruit. Besides the well-known red-fruited, there are thewhite or yellow-fruited, the stoneless, the violet, purple or black-fruited, and the sweet-fruited, erroneously so called, for it is scarcely less acid than the common barberry, with which it agrees in the colour of the fruit, but the leaves are shining and of a brighter green. This variety is found wild in Austria.

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The Barberry is interesting to naturalists on account of a remarkable property of its stamens. The irritability of these organs is such, that when the point of a pin is lightly applied to the filaments, they bend forward towards the stigma, and afterwards partially rise again. Experiments, with different powerful agents, have been tried, and it is found that this irritability is destroyed by poison. Arsenic and corrosive sublimate render the filaments too stiff and brittle to act, while prussic acid, opinm, and belladonna make them too relaxed and flaccid. From these curious facts, it is inferred that there is in plants something analogous to the nervous system in human beings, and that in both cases it is more highly developed in some individuals than in others.

The barberry is infested by a minute fungus or blight, (JZcidium berberidis,) which fixes on the tenderest parts, and scatters, from thousands of small tubular openings, the orange-coloured dust which is so commonly seen on the leaves and flowers of this plant. This dust consists of a countless multitude of sporules, and it is their presence, doubtless, which has given rise to the idea that the barberry communicates blight to wheat fields. The rust which infests corn is indeed of the same colour as the barberry blight, but it is quite a different fungus, and the one can never propagate the other. Supposing, therefore, that there are any grounds for the popular opinion as to the injurious nature of barberry bushes to wheat, these are yet unexplained, and cannot be assigned to the presence of the parasite.

BARGE-BOARDS. The inclined projecting boards placed at the gable of a building, and hiding the horizontal timbers of a roof. They are frequently carved with various ornaments.

BARGE-COUPLES are two beams mortised and tenoned together for the purpose of increasing the strength of a building.

BARGE COURSE. The part of the tiling which projects over the gable of a building, and which is made good below with mortar.

BARILLA. [See Soda.]

BARIUM. The metallic basis of baryta. It may be obtained by strongly heating baryta in an iron tube through which the vapour of potassinm is conveyed. The potassinm combines with the oxygen of the baryta, and reduces the barinm, whioh may be extracted by mereury and distilling the amalgam in a small green-glass retort. Barinm is a white metal with the colour and lustre of silver; it is malleable, fuses below a red heat, decomposes water and oxidizes in the air. Its equivalent is 68.55, and its symbol is Ba.

The oxide of Barinm, BaO, called baryta or barytes, occurs abundantly in nature as carbonate and sulphate, forming the vein-stone in many lead mines. Pure baryta may be obtained by decomposing the crystallized nitrate at a red heat. The baryta is a greyish spongy mass, fusible at a high degree of heat. It forms a hydrate with water, with great elevation of temperature. The hydrate is a white soft powder, which has a great attraction for carbonic acid, the

smallest trace of which renders its solution instantly turbid. Water, saturated with carbonic acid, dissolves tfjrrth part of baryta, forming what is called baryta wuter, which is a useful test for carbonic acid. Of all the bases, baryta has the strongest affinity for sulphuric acid, and is, therefore, used either in the state of baryta water or in that of one of its neutral salts, as the nitrate or muriate, to detect the presence and determine the quantity of that acid in any soluble compound. The peroxide of Barinm, BaOj, has not much interest in the useful arts, and indeed, the whole subject of this article belongs rather to scientific chemistry. The sulphate of baryta, or heavy spar, BaO, SO3, is used as a pigment under the name of permanent white, but chiefly for the purpose of adulterating white lead; but as it does not form a body with linseed oil, its presence is injurious. Sulphate of baryta, on account of its cheapness ana weight, is also employed in other cases of adulteration. The native sulphate was employed by Wedgwood in the manufacture of jasper ware, and for the production of opaque white patterns and figures upon a coloured ground. The specific gravity of the native sulphate is as much as 4.7, and that of baryta is about 4; hence its name, as being the heaeiest (jiapvt, heavy) of the substances usually called earths. Nearly all the barytic compounds are poisonous, but the sulphate of baryta is harmless; the best antidote, therefore, for the soluble barytic salts', is a solution of sulphate of soda.

BARK. The outer rind of plants, which in some cases yields an astringent principle called tannin, highly useful in medicine and the arts. The most important kinds of bark in a commereial point of view are undoubtedly Oak-bark and Peruvian bark. Oak-bark was for a long time the only substance used in England for tanning leather, and is still preferred before all other substances, although lareh-bark has come into extensive use. Oak-bark is powerfully astringent, and would probably have remained the sufficient and only tanning material, had there not been a failure in the supply, which induced a seareh after other substances, and led to those experiments of the scientific of former days, and latterly of Sir Humphry Davy, by which several other barks yielding tanning materials were brought conspicuously into notice. Davy has ascertained the relative value of various substances in this respect, showing that 3-Jribs, of oak-bark are equal to 2\ lbs. of galls, to 31bs. of sumach, to 7\ lbs. of the bark of the Leicester willow, to 11 lbs. of the bark of the Spanish chestnut, to 18 lbs of elm-bark, and to 21 lbs. of common willow-bark. The importation of common oak-bark has somewhat declined of late years, but is still very considerable from Belginm, Holland, Germany, Italy, Spain, Norway, and Australia. There is a kind of oak-bark imported from the United States, called Quereitron, the produce of the Quereus iinctoria, used in tanning, and also in giving a yellow dye to silk and wool. The colouring matter obtained from this bark is equal to that obtained from eight or ten times its weight of weld. The useful properties of Quercitron were discovered and applied by Dr. Bancroft, who patented his invention in 1775. In the parliamentary returns of the quantity of oak-bark imported into this kingdom, there is no distinction made between oak-bark for tanning and dyeing purposes. The quantity imported in the year 1842, was upwards of 639,429 cwt.; and the duty amounted to 13,400/. The proportion of tannin in oak-bark varies greatly with the season in which it is cut, and with the age of the tree. Young trees barked in spring yield by far the largest amount. The operation of barking is thus performed:—When the tree is felled, and before it has been deprived of its larger branches, the whole are stripped of their bark by women called barkers, each furnished with a light short-handled mallet made of hard wood, the face of which is about 3 inches square, and the other end sharpened like a wedge. With the sharp part an incision is made along the side of the tree in a straight line, while cross-cuts are also made with a pointed instrument called the barking-bill. A shovelshaped instrument called a peeling-iron is then forced between the bark and the wood, separating the former without difficulty in entire pieces. These are carefully dried for two or three weeks, and then piled in stacks and sold to the tanner.

Next in importance to oak-bark, is the Peruvian or Jesuits' Bark, well-known as a valuable medicine. Of this there are three principal species, known in commerce as pale, red, and yellow bark. The first is the produce of Cinchona lancifolia, and is the original cinchona of Peru. It is received in chests covered with skins, each containing about 200 lbs., consisting of pieces 8 or 10 inches long, and singly or doubly quilled, or rolled inwards. It is of a pale fawn or cinnamon colour, and has very little odour while dry, but the decoction is agreeably aromatic. The taste is a fine bitter, but austere. This species is becoming more and more scarce. The second, or red bark, is obtained from Cinchona oblongifolia, growing on the Andes, and is received in chests weighing from 100 to 150 lbs. each. This kind is mostly in flat pieces of various sizes, with occasionally some that are quilled; the internal part being woody, and of a rust red colour. Red bark has a weak peculiar odour, and a less bitter, but more nauseous taste than the other barks. The third, or yellow bark, is the produce of Cinchona cordifolia, growing in Quito and Santa Fe. The chests contain from 90 to 100 lbs. each, in pieces from 8 to 10 inches long, some quilled, but the greater part flat. The interior is yellow approaching orange-colour. It has nearly the same odour in decoction as the pale, and has a more bitter and less austere taste. If the colour of the specimen be variable, it is not of the first quality, and if it be dark between red and yellow, it should be rejected. The medical uses of Peruvian bark are said to have been first discovered by the Jesuits. This important substance was brought to Europe in 1632, but was not much used till the latter end of the seventeenth century. Humboldt estimates the quantity now annually exported from America at from 12,000

to 14,000 quintals. In the pale Peruvian bark there exists a principle called cinchonia, and in the yellow bark an analogous but distinct principle called quinia, both of which are obtainable by a somewhat expensive process, and are abundantly prepared for medical use. The valuable properties of the bark are thus available in a concentrated form. Sulphate of Quinia or Quinine is now an object of especial attention, and is manufactured both in this country and on the continent to a very great extent. The annual export from Paris alone, is estimated at 120,000 ounces.

BARLEY. An important grain for malting purposes, but a bad bread corn: "Grossier comme pain d'orge" is a French proverb. Barley is extensively cultivated in most temperate climates, and is even raised within the tropies, but not at a lower elevation than about four thousand feet. The principal sowing season in our own country is in March or April, according to the situation. This crop generally follows turnips, potatoes, or pulse, and is important in the rotation adapted to light soils. It seldom follows wheat and oats, unless after three ploughings, and then ordy under certain circumstances. The produce varies, according to season, situation, and preparation of the sdil, from 20 to 60 or 70 bushels per acre. From 30 to 40 bushels is a usual crop. The nutritive matter obtained from barley is reckoned at 65 per cent.; that of wheat at 78 per cent. A bushel of barley, weighing 50lbs., will consequently contain about 32 lbs. of nutriment. The barley crop is of great importance in England, and occupies the ground about four months. The best barley counties are the middle line of counties from east to west. In Egypt and similar genial climates two crops of barley may be raised in the same year; one in spring, from seed sown the previous autumn, and one in autumn, from a spring sowing. By the hail which desolated Egypt during the sojourn of the children of Israel "the flax and the barley were smitten: for the barley was in the ear, and the flax was boiled. But the wheat and the rye were not smitten: for they were not come up."—Exod. ix. 31. This event is computed to have happened in the month of March, at which time the first crop of barley was nearly ripe, and the flax ready to pull. But the wheat and rye sown in spring were not sufficiently forward to receive injury.

Pot barley is barley deprived of its outer skin. Pearl barley, also called Scoteh or French barley, is barley deprived not only of the skin, but of a portion of the grain, leaving merely a small round kernel. Both preparations are made by means of the same kind of mill, but the pearl barley receives a greater degree of the grinding process. The grain is kiln-dried before it is ground. The simplest form of mill, and that which is now in use on the Continent, resembles a common flour-mill, with two mill-stones, each about three feet in diameter, one fixed, the other revolving over it. The upper stone has six grooves cut in the lower surface, from the centre to the circumference (Fig. 92), and a perforation in the centre. It revolves on a vertical axis of iron, the lower point of which moves in a metal cup fixed on an clastic horizontal beam.

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The upper stone moves parallel to the lower, and so Fig. 92. close to it as to rub

without crushing the grain which passes between them. The mill is fed by a hopper, through the central I opening, as in the common corn-mill. The stones work in a cylindrical box or case, the top of which is of wood, with a cireular opening corresponding to that of the stones. The cireumference of the box is of thin iron plates, punched with numerous holes, so as to resemble a nutmeggrater, the rough surface of which is within, and assists the operation of removing the skin from the barley. Before being placed in the hopper, the barley is slightly moistened with water, and turned two or three times, in order to loosen the skin; it is then gradually supplied by the hopper to the action of the stones: it enters the grooves in the upper stone, and is whirled round at the rate of two or three hundred revolutions per minute, thus breaking the skin, and strongly rubbing, but not crushing, the grain against the under stone. It is then driven off with considerable foree against the grating surface of the cylinder, which, together with the current of air produced in the process, completely removes any remaining skin from the grain. From the cylinder it is let out through a square opening, and falls on a sieve, where the naked barley is separated from the bran. The greater part of the fine particles of barley escape through the holes in the cylinder during the process; therefore, to avoid waste, a cloth is fastened round the cylinder, and guides the meal into a bin below. This mill answers very well for pearl barley, but for simply removing the skin, or making pot barley, it has these disadvantages,—that it requires great nicety in the adjustment of the stones, and that, with every precaution, the barley is ground unequally, the larger grains losing more of their substance than is desirable.

The supply of pearl barley to this country, and indeed to the rest of Europe, was formerly a Dutch import; hence it was called Dutch pearl barley; but at present the manufacture is largely carried on within our own dominions, and we receive the larger portion of our pot and pearl barley from Scotland. The mill commonly used in that country consists of one ordinary grindstone, such as cutlers use, revolving on a horizontal axis, passing through the centre of an outer case, shown in section abed, and entire in Fig. 94, which moves at a slower rate, by the means shown in Fig. 94. The outer case is moved by a pinion M fixed to the spindle R, at the opposite end of which is a drum, connected by an endless band with the moving power. The stone I is also moved by a similar contrivance. The pinion M is fixed to the spindle R by means of a brass bush fitted into the centre of the pinion, and then bored exactly to fit a

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conical place in the spindle R. Below the base of the cone is a brass ring 3, to keep the pinion M firm upon the cone by means of four screw-bolts which bring the pinion firmer to the base of the cone. On the other side the pinion are two projections or snags, 1, which take into similar projections on the end of the catch 2 5. This catch slides along the spindle R by moving the lever N, but goes round with the spindle by means of two tongues fixed on r the opposite sides . of the spindle, one of which is partly visible at 4. Two grooves are cut in the inside of the catch, to admit the tongues, in order to carry the catch round with the spindle. The wheel N O, having 102 teeth, and a diameter of 4 feet \\ inches to the pitch stroke, is screwed to the sides of the drum that incloses the stone. This drum, which is shown in section ab c rf, is lined with milled iron, piereed with small holes, in order to permit the escape of the dust, and to act as a grater to the barley.

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Fig. 94.

When the drum is turned round by the wheels already described, it is supported and kept clear of the stone by the collars h i. The collar h is larger than i, in order to give room to the spout p, to fill the drum with barley. This is effected by a thin plate of iron k, about an inch larger in diameter than the inside of the collar, which is kept close to the side of the collar next the stone by the staple / on each side of the stono spindle. The other end of it is kept fast by the cover of the pillow-block m. In the plate k a hole is cut for the end of the spout. When the barley is made, the drum is stopped by

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