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and the curtain, in which the instrumental

erformers sit.

ORCHIDEAE, in botany, the seventh order in Linnaeus's Fragments of a Natural Method, consisting of Orchis, and the plants that resemble it in habit, powers, and sensible qualities. The flowers are hermaphrodite, and placed at the summit of the stalk, either in a spike, or in a panicle. Each flower is accompanied with a leaf that is smaller than the other leaves, and forms a sort of sheath round the stalk. The petals are five in number, and very irregular. The flowers of the different species are remarkably various and singular in their shape, resembling different kinds of animals or insects.

ORCHIS, in botany, a genus of the Gynandria Diandria class and order. Natural order of Orchideae. Essential character: nectary a horn or spur behind the flower. There are fifty species. Among which we shall notice the O. bifolia, but. terfly orchis. This plant has ovate bulbs, tapering to a point at the base; thick fleshy fibres proceed above them from the base of the stem ; one of these bulbs is always wrinkled and withered, whilst the other is plump and delicate; the first is the parent of the actual stem ; the second is an offset, from the centre of which the stem of the succeeding year is destined to arise. Such are the means that nature uses, not only to disseminate plants, but to enable them to change their place, and thus to draw in fresh nutriment. The second root is always about half an inch from the centre of the first, so that in twenty years the plant will have marched ten inches from the place of its birth. This mode of increase is particularly necessary in a family of plants that rises with great difficulty, and very seldom by seed. O. conopsea, long-spurred Orchis, is distinguished by the remoteness of the cells or cases in which the stamens are lodged, and again by the colour of the corolla, the great length of the spur, the delicious fragrance of its flowers, vying with that of the honeysuckle, and particularly by the unusual structure of its flowers. Below the stigma, which is remarkably well defined in this species, there is a circular opening between the cavities containing the stamens; just above the stigma is a very conspicuous ridge; the stamens soon change to a brownish hue ; the anthers are club-shaped, and are divided as in most others, the gland at the base of the filament is of a circular form, with a cavity on its inner side: the roots of this species are well calculated for making salep.

ORDEAL, was anciently a form of trial, ... and was of two sorts; either fire ordeal, , , or water ordeal; the former being con. . fined to persons of higher rank, the lat. ter to the common people. Both these might be performed by deputy, but the principal was to answer for the success ... of the trial; the deputy only venturing to some corporeal pain for hire, or perhaps ... for friendship. Fire ordeal was perform. ... ed either by taking up in the hand a piece of red hot iron, of one, two, or three pounds weight; or else by walking barefoot and blindfold over nine red hot ploughshares, laid at unequal distances; and if the party escaped unhurt, he was adjudged innocent; if not, he was condemned as guilty. Water ordeal was performed, either by plunging the bare arm up to the elbow in boiling water, and es: caping unhurt thereby, or by casting the person suspected into a river or pond of water; and if he floated, without any at: tion of swimming, it was deemed an evi. dence of his guilt; but if he sunk he was acquitted. The trial by ordeal was abo. lished by parliament anno 3 Henry Ill. ORDER, in architecture, is a system of the several members, ornaments, and proportions of columns and pilasters; or a regular arrangement of the projecting parts of a building, especially the column, so as to form one beautiful whole. There a are five orders of columns, of which three so are Greek, viz. the Doric, Ionic, and C0, s. rinthian, and two Roman, the Tuscan and o Composite. The three Greek orders re. ... present the three different manners of building, viz. the solid, the delicate, and 's that which is between the two. See All chitecture. - - Onden, in astronomy. A planetis said to go according to the order of the signs when it is direct, proceeding from Aries to Taurus, thence to Gemini, &c. It goes contrary to the order of the signs, when it is retrograde, or goes backward from Piš' ces to Aquarius. ORDER, in geometry, is denominated from the rank or order of the equation by which the geometrical line is expressed: thus, the simple equation, or first power, denotes the first order of lines, which is a right line : the quadratic equation, or * cond power, defines the second order" lines, which are the conic sections and circle: the cubic equation, or third pow; er, defines the third order of lines; and so on. Or the orders of lines are denom: nated from the number of points in which they may be cut by a right line. This the right line is of the first order, becau. it can be cut only in one point by a rig"

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line: the circle and conic sections are of the second order, because they can be cut in two points by a right line; while those of the third order are such as can be cut in three points by a right line. ORnER, in botany, the first subdivision of a class in the Linnaean system, founded on the number of styles or female organs. The orders of Linnaeus are all expressed by a single term, which, like the names of the classes, is of Greek etymology, and is significant of the character of the order to which it is applied. The names of these orders are often different in different classes, because the same idea predominates in their institution. ORDINANCE, or Ordonnancé, a law, statute, or command of a sovereign or superior. ORDINARY, in the civil law, signifies any judge that hath authority to take cognizance of causes in his own right, as he is a magistrate, and not by deputation; but in the common law, it is taken for him who has exempt and immediate jurisdiction in causes ecclesiastical. ORDINARY, or honourable Ordinary, in heraldry, a denomination given to certain charges properly belonging to that art. The honourable ordinaries are ten in number; viz. the chief, pale, bend, sesse, bar, cross, saltier, chevron, bordure, and orle. For which see HERALDRY, &c. ORDINATES, in geometry, are right lines drawn parallel to each other, and cutting the curve in a certain number of points. Parallel ordinates are usually all cut by some other line, which is called an absciss. When this line is a diameter of the curve, the property of the ordinates is then the most remarkable ; for, in the curves of the first kind, or the conic sections and circle, the ordinates are all bisected by the diameter, making the part on one side of it equal to the part on the other side of it; and in the curves of the second order, which may be cut in three points by an ordinate ; then of the three parts of the ordinate, lying between these three intersections of the curve and the intersection with the diameter, the part on one side the diameter is equal to both the two parts on the other side of it. And so for curves of any order, whatever the number of intersections may be, the sum of the parts of any ordinate, on one side of the diameter, is equal to the sum of the parts on the oth. er side of it. The use of ordinates in a curve, and their abscisses, is to define or express the nature of a curve by means ef the general relation or equation be

tween them; and the greatest number of factors, or the dimensions of the highest term, in such equation, is always the same as the order of the line; that equation being a quadratic, or its highest term of two dimensions, in the lines of the second order, being the circle and conic sections; and a cubic equation, or its highest term containing three dimensions, in the lines of the third order, and so on. Thus, y denoting an ordinate, and ac its absciss, also a b c, &c. given quantities: then y' = a aco + b x: + c is the general equation for the lines of the second order: and a y” e y = a x2 + b x* + c ac-H d is the equation for the lines of the third order, and SO On. ORDINATION, the act of conferring holy orders, or of initiating a person into the priesthood, by prayer, and the laying on of hands. Ordination has always been esteemed the principal prerogative of bishops, and they still retain the function, as a mark of spiritual sovereignty in their diocese. Without ordination, no person can receive any benefice, parsonage, vicarage, &c. A clerk must be twenty-three years of age before he can have any share in the ministry; and twenty-four before he can be ordained, and by that means be permitted to administer the sacraments. A bishop, on the ordination of clergymen, is to examine them in the presence of the ministers who assist him at the imposition of hands: and in case any crime, as drunkenness, perjury, forgery, &c. be alleged against any one that is to be ordained, either priest or deacon, the bishop ought to desist from ordaining him. The person to be ordained is to bring a testimonial of his life and doctrine to the bishop, and give an account of his faith in Latin, and both priests and deacons are obliged to subscribe the thirty-nine articles. ORDNANCE, a general name for all sorts of great guns used in war. QRDNANCE, office of, an office kept within the Tower of London, which superintends and disposes of all the arms, instruments, and utensils of war, both by sea and land, in all the magazines, garrisons, and forts, in Great Britain. The officers of the ordnance are: 1. The Master General, from whom are derived all orders and despatches relating to the same. 2. The Lieutenant Gene. ral, who receives orders from the Master General, and sees them duly executed; orders the firing of guns on days of rejoicing, and sees the train of artillery fitted out when ordered to the field. 3. The Surveyor General, who has the inspection of the ordnance, stores, and provisions of war in the custody of the store-keepers; he allows all bills of debt, keeps a check on labourers, &c. 4. The Treasurer, through whose hands passes the money of the whole office, as well for payment of salaries as debentures; as also a Clerk of the Ordnance, and a Clerk of the Deliveries, for which see the articles, CLERK of the ordnance, &c. ORES, in mineralogy. An ore is a metal in the state in which it exists in the earth. It may be either native, that is, pure, and uncombined with any other substance, or alloyed with another metal; or in a state of an oxide, or a sulphuret, or a carburet, or of a metallic salt. It is also mixed in most instances with various earthy minerals. The ores of metals may be analyzed in two modes, in the humid and the dry way. The first is effected with the aid of acids, and of other liquid agents, and may often be accomplished by very simple means, and without the aid of a bulky and expensive apparatus. If sulphur be present, it impedes the action of acids, and should be separated by roasting the ore on a muffle, or by projecting it mixed with twice its weight of nitre into a red-hot crucible, washing off the alkali afterwards with hot water. No solvent will act upon all the metals. Thus nitric acid does not act on gold and platina; and the nitro-muriatic acid, which dissolves these metals, has no solvent action on silver. Hence the necessity of varying the solvent according to the nature of the ore under examination. We shall give a few instances, by which the reader will understand the theory, and may be enabled to verify the facts by practice. For “ores of gold and platina,” the nitro-muriatic acid is the most proper solvent. A given weight of the ore may be digested with this acid, as long as it extracts any thing. The solution is to be evaporated to dryness, in order to expel the excess of acid, and dissolved in water. The addition of a solution of tin and muriatic acid will shew the presence of gold by a purple precipitate; and platina will be indicated by a precipitate, on adding a solution of muriate of ammonia. When gold and platina are both contained in the same solution, they may be separated from each other by the last mentioned solution, which throws down the platina, but not the gold. In this way

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platina may be detached also from other metals.

For extracting “silver” from its ores, the nitric acid is the most proper solvent. The silver may be precipitated from nitric acid by muriate of soda. Every hundredth part of the precipitate contains seventy-five of silver . But, as lead may be present in the solution, and this metal is also precipitated by muriate of soda, it may be proper to immerse in the solution a polished plate of copper. This will precipitate the silver, if present, in a metallic form. The muriate of silver is also soluble in liquid ammonia, which that of lead is not.

“Copper ores” may be analyzed by boiling them with five times their weight of concentrated sulphuric acid, till a dry mass is obtained, from which water will extract the sulphate of copper. This salt is to be decomposed by a polished plate of iron, immersed in a dilute solo tion of it. The copper will be precipi. tated in a metallic state, and may be scraped off and weighed. If silver be suspected with copper, nitrous acid must be employed as the solvent; and a plate of polished copper will detect the silver.

“Iron ores” may be dissolved in dilute muriatic acid, or, if the metal be too highly oxydized to be dissolved by this acid, they must be previously mixed with one-eighth of their weight of powdered charcoal, and calcined in a crucible for an hour. The iron is thus rendered soluble. The solution must then be diluted with ten or twelve times its quantity of water, previously well boiled, to exp: the air, and must be preserved in a well. stopped glass bottle for six or eight do The phosphate of iron will within that time be precipitated, if any be present, and the liquor must be decanted off. The solution may contain the oxides of iro", manganese, and zinc. It may be pres: pitated by carbonate of soda, which will separate them all. The oxide of zino will be taken up by a solution of pure ammonia; distilled vinegar will take up the manganese, and will leave the ox.” of iron. From the weight of this, after ignition, during a quarter of an ho only eight per cent. may be deduck ed.

“Tin ores.” Boil 100 grains, in a sil. ver vessel, with a solution of 600 gra" of pure potash. Evaporate to dry.” and then ignite moderately for half " hour. Add boiling water, and if any portion remain undissolved, let it unders" a similar treatment. Saturate the alkaline solution with muriatic acid, which will throw down an oxide of tin. Let this be redissolved by an excess of muriatic acid; again precipitated by carbonate of soda; and being dried and weighed, let it, after lixiviation, be once more dissolved in muriatic acid. The insoluble part consists of silix. Into the colourless solution, diluted with two or three parts of water, put a stick of zinc, round which the reduced tin will collect. Scrape off the deposit, wash, dry, and fuse it under a cover of tallow in a capsule placed on charcoal. A button of pure metallic tin will remain at the bottom, the weight of which, deducted from that of the ore, indicates the proportion of oxygen. The presence of tin in an ore is indicated by a purple precipitate, on mixing its solution in muriatic acid with one of gold in nitro-muriatic acid. “Lead-ores” may be analysed by solution in nitric acid, diluted with an equal weight of water. The sulphur, if any, will remain undissolved. Let the solution be precipitated by carbonate of soda. If any silver be present, it will be taken up by pure liquid ammonia. Wash off the excess of ammonia by distilled water, and add concentrated sulphuric acid, applying heat, so that the muriatic acid may be wholly expelled. “Mercury” may be detected in ores that are supposed to contain it, by distillation in an earthen retort with half their weight of iron filings or lime. The mercury, if any be present, will rise and be condensed in the receiver. “Ores of zinc” may be digested with the nitric acid, and the part that is dissolved boiled to dryness, again dissolved in the acid, and again evaporated. By this means, the iron, if any be present, will be rendered insoluble in dilute nitric acid, which will take up the oxide of zinc. To this solution add pure liquid ammonia, in excess, which will separate the lead and iron, if any should have been dissolved; and the excess of alkali will retain the oxide of zinc. This may be separated by the addition of an acid. “Antimonial ores.” Dissolve a given weight in three or four parts of muriatic, and one of nitric acid. This will take up the antimony, and leave the sulphur, if any. On dilution with water, the oxide of antimony is precipitated, and the iron and mercury remain dissolved. Lead may be detected by sulphuric acid. “Ores of cobalt” may be dissolved in nitro-muriatic acid. Then add carbonate WOL. IX:

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of potash, which, at first, separates iron and arsenic. Filter, and add a further Quantity of the carbonate, when a greyish red precipitate will fall down, which is oxide of cobalt. The iron and arsenic may be separated by heat, which volatilizes the arsenic. Cobalt is also ascertained, if the solution of an ore in muriatic acid give a sympathetic ink. See Klaproth’s Essays. . To analyze ores in the dry way, a method which affords the most satisfactory evidence of their composition, and should always precede the working of large and extensive strata, a more complicated apparatus is required. An assaying furnace, with muffles, crucibles, &c. are absolutely necessary. See AssaxING, LAbonaTon Y, &c. The reduction of an ore requires frequently previous roasting, to expel the sulphur and other volatile ingredients; or this may be effected by mixing the powdered ore with nitre, and projecting the mixture into a crucible. The sulphate of potash, thus formed, may be washed off, and the oxide must be reserved for subsequent experiments. As many of the metals retain their oxygen so forcibly, that the application of heat is incapable of expelling it, the addition of inflammable matter becomes expedient. And to enable the reduced particles of metal to agglutinate and form a collected mass,instead of scattered grains, which would otherwise happen, some fusible ingredient must be added, through which, when in fusion, the reduced metal may descend, and be collected at the bottom of the crucible. Substances that answer both these purposes are called fluxes. The alkaline and earthy part of fluxes serve also another end, viz. that of combining with any acid which may be attached to a metal, and which would prevent its reduction, if not separated. The ores of different metals, and different ores of the same metal, require different fluxes. See FLUx. The ore, after being roasted, if necessary, is to be well mixed with three or four times its weight of the flux, and put into a crucible, with a little powdered charcoal over the surface. A cover must be luted on, and the crucible exposed to the necessary heatin a wind furnace. Ores of iron, as being difficultly reduced, require a very intense fire. Those of silver and lead are metallized by a lower heat. The metal is found at the bottom of the crucible, in the form of around button. The volatile metals, as mercury, zinc, arsenic, tellurium, and osmium, it is obvious, ought

not to be treated in the above manner, and require to be distilled with inflammable matters in an earthen retort. See Kirwan's Mineralogy. ORGAN. Having, under the article Musical instruments, given a pretty full account of this instrument, we shall here only give a description, with figures, of the barrel-organ. See Plate I. Barrel Organ, and Plate II. parts of ditto. The barrel-organ is generally portable, and is so contrived, that the same action of the hand, which turns the barrel, suplies the wind, by giving motion to the §. : it consists of three principal parts: 1. The pipes, by which the sound is produced. 2. The bellows, supplying them with air. 3. The barrel and keys, by which the pipes are sounded at proper intervals. The pipes, are of two kinds, of metal and of wood: the wooden ones are a square trunk of deal wood, A B, (fig. 5) closed at one end by a plug of wood, D, and at the other by a piece of wood, E, containing a crooked passage to bring air to the pipe, through the short tube, P; a is a piece of oak board, glued to the block E, and hollowed out to communicate with the crooked passage in it, and leaving a small crack, between it and the edge of the block, E, through which the air issues in one continued stream; in its passage it is divided by the edge of one side of the trunk, A, which is cut as sharp as possible for that purpose, and which is exactly in the same line with the orifice whence the air is emitted. The sound is produced by the vibration of the air which is contained in the trunk, A, and by increasing or diminishing the length of the pipe, the tone is altered at pleasure, to bring it to the proper note it is to perform when placed in the instrument: this is done by sliding the plug, D, up or down in the pipe. A metal pipe, a section of which is shown in fig. 6, is nearly the same in its operation, though different in its construction. It is a cylindrical tube, of a mixture of lead and tin; A B (fig. 6.) open at one end, and nearly closed at the other by a lump of the same metal, E, which is circular for about two-thirds round, and fits the end of the pipe; the other third is a straight edge: the upper edge of the conical pipe, F, is bent to be parallel to this, and thus forms a small cleft similar to the wooden one, for the passage of the air; the lower edge of the cylindrical pipe, A B, is bent into the line of the cleft and cut sharp, to divide the current of air; these pipes are open

at top, and are brought to tune by bending the pipe at the top, and thus altering its bulk : a is a piece of metal, called the ear, soldered upon the pipe at each end of the cleft, to prevent the stream of air being dispersed before it meets the sharp edge of the pipe, B.A.; in the small pipes this is not applied. The bellows of the organ are double, as shewn in fig. 1, Plate I; that is, they are two distinct pairs, E, F, connected together at their hinge; so that when one is opening, and filling with air, the other is forcing its air out into the regulator, D; the bellows receive their motion by a rod, d, from a crank, a, on a spindle which comes through the box, in which the machine is enclosed, and has a handle on it by which it is turned. The regulator, D, is exactly similar to another pair of bellows, and is filled with air from the bellows, E F, below it, through two valves in the bottom board over the bellows; from this regulator the air proceeds through the passage, be f, (seen better in the section), fig. 2, &c. Fig. 2, Plate I. to a long trunk, g, going under the pipes called the air-chest, which communicates with them by a small valve, h, under each; it is kept shut by a small wire spring, and is opened by a wire fixed to the end of a rod, G; above the valve, the passage enlarges, and goes under two small wooden sliders or stops, n m, and from thence in two distinct passages to the wooden and metal pipes, N. M. The air-chest, g, is common to all the pipes, and each pair (of wooden and metal pipes) has a valve, h, and spring to themselves; the small passage above each valve belongs to id: pair of pipes, and has no connection with the other; the two stops belong to all the pipes; m to the metal, and n to the wooden ones; they are long slips of wood drilled with so many holes as there are pipes, and at the same intervals, (the disposition of the pipes is shewn in fig. 3, which is a plan of the whole instrument put together); so that when the holes are over the pas. sages, the air has free communication from the valve to the pipes; but when the stops are drawn out, the interval be. tween each hole applies itself to the holes under the pipes, and thus stops the passages. We now come to describe the appara. tus which opens the valves, h, at the proper time, to perform the note of a piece of music. The axle, on which the crank, a, (fig. 1, 2, and 3.) is formed, has an endless

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