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Composite Capital, with
Acanthus Ornament.

States are chiefly tender garden or hothouse plants, as'Justicia, Thunbergia, etc.

Acanthus, in architecture, a conventionalized leaf decoration believed to have been designed after the leaf of the acanthus spinosus. It is seen in characteristic form in the Corinthian capital of ancient Grecian architecture. The Roman acanthus is more of the type of leaf of the acanthus mollis. In modified forms the acanthus also served for the decoration of furniture, laces, vases, and personal ornaments. See Architecture.

A cappeUa, or Alla Cappella, a musical term implying that a composition is to be sung as ecclesiastical music. Frequently it means that the voices are unaccompanied, or accompanied only by an instrument (usually the organ} played in unison with the voices.

Acapulco, port in Guerrero, Mexico, on the Pacific Ocean, 230 m. southwest of Mexico City. It lies among low hills, and the climate is hot all the year round. It has one of the finest harbors in the world, a semi-circular bay covering about 8 square miles and with 16 fathoms of water. The region is subject to earthquakes, and Acapulco was partly destroyed by a series of shocks in 19O9. Exports hides, cedar, and fruits. Pop. 5,800.

Acarlna, an order of arachnids. See Mites; Tick.

Acarnanla, district. Northwest Greece; witruEtolia it forms the province (nomarchy) of Acarnania and ^Etolia, stretching north from the Gulf of Patras, and including part of the Gulf of Arta. Area, 3,034 sq. m. The western part is covered with woods, and the soil is rich. There are many fruit orchards. The finest tobacco country of Greece is the plain of Agrinion in

Vol. I.—Mar. '12

Acarnania. Lake Trichonis lies in a famous region. Pop. 175,000.

A cams (Demodei) Folllc

ulorum, a minute parasitic mite which infests the hair follicles and sebaceous glands in man. It is very common, and seems to have no influence upon health. The size varies from one-fiftieth to one-hundredth of an inch; and as in mites in general, four pairs of legs are present, here rudimentary. See Mites.

Acatalectlc Measures, metres which do not allow of the excision of an unaccented syllable at the beginning or the end of the line. See Catalectic.

Accad. See Akkad.

Accault, Michel, a Frenchman who, with an explorer named Du Gay, accompanied Father Hennepin, at the instance of La Salle, in Hennepin's discoveries in the upper waters of the Mississippi. In 1680 all three were made prisoners by a wandering band of Sioux.

Accelerando (Italian), a musical term indicating that the tempo is to be gradually increased.

Acceleration, the rate at which the velocity of a moving body changes. It is positive when the velocity is increasing, negative (with the minus sign) when it is decreasing. The acceleration of a falling body, due to gravity, amounts to 32.2 feet per second. If the body influenced by gravity is moving upward, as a ball thrown into the air, its acceleration by gravity is negative, and is represented by —32.2 feet per second. See Kinematics; Kinetics.

Accent, the stress laid in pronunciation upon one syllable of a word—corresponding to emphasis, the stress laid in elocution upon a word or words in a phrase. In Indp-Germanic languages accent is either musical (consisting of higher or lower tones, as in Sanskrit and Greek) or expiratory (consisting of simple stress, as in English). In Old English the first syllable of simple words bore the accent, and the inflectional parts remained jnaccented, as now— e.g., love, lovable, Idveliness. Again, nouns compounded with a prefix threw the accent back on the prefix; but verbs similarly compounded retained their former accent. Thus in modern English we say outcome (noun), but outdo (verb). This principle was extended to words borrowed from other languages, and hence we have such pairs as decent (noun) and accent (verb), perfume (noun) and perfume (verb).

Words taken from other languages generally conform to the same principles as native Germanic words—i.e., they throw the accent as far back as possible toward the beginning of the word.

Most English words have only one accent, but in the case of long words, like dissimulation, we may also have a secondary accent. This accent is scarcely perceptible in ordinary speech, but is of considerable importance for metrical purposes.

The English habit of slurring over the unaccented syllables of a word has given us some of our most curious derivations, such as 'proxy,' from French procuracie, and 'alms,' from Greek eleemosyne. In like manner, accent has been one of the chief factors in inflectional and phonetic decay, and is probably one of the chief factors of ablaut (q.v.).

For accent in its metrical aspect, see Verse.

Accent, a grammatical sign used to distinguish the varying sounds of the same vowel. They are three in number—viz., grave ('), acute ('), and circumflex (*), as exhibited in the French words pere. lie, tele.

Accent, in music, is the regular recurrence of stress or emphasis upon certain notes—always (unless syncopated) upon the first note of a bar; while a slighter accent falls on the third note of a bar in common time, or the fourth in a bar of f time.

Acceptance. See Bills Anb Notes.

Access, Bight of. A legal right, in the nature of an easement, which a riparian owner possesses, of uninterrupted access to the sea or navigable river. This is a right of property, and cannot be cut off through the grant by the state of the shore to a railroad company or other private owner. See Riparian Rights.

Accession. In law the mode of acquiring property by the natural or artificial increase, addition to, or improvement of things already ours. Thus the owner of land becomes entitled to plants and trees growing upon it, and to the increase or addition to it arising from accretion and alluvion; the offspring of animals belong to the owner of the mother. When the increase or improvement is artificial, as by the addition to our property of the property or work of others (houses built on our land, or embroidery worked on our cloth), the owner of the principal thing is entitled to what was accessory to it, subject generally to the Accessories

pavment of compensation, and subject also to certain exceptions. For example, when the result of expending work upon another's goods is the production of a new thing, the rule is reversed, so Chat when a man makes wine from inother1 s grapes, he keeps the wine and pays for the grapes; again, when an artist paints a picture on the canvas of another, he keeps the picture and pays for the canvas. These doctnnes were fully worked out in the Roman law. The English and American law differ from the Roman only in making a distinction between the innocent and the wilful transformation of a man's property hy accession, permitting him in the case of wilful accession to recover his goods even though they have been changed by the wrongdoer into something of a different nature—as grain into whiskcv. On the other hand in the United States a great increase in the value of a chattel, as in the conversion of standing timber into barrel hoops, if innocently done, transfers the title as effectually as would a complete change in the nature of the property.

Accessories, the paraphernalia, other than the shield, of a heraldic achievement—viz. the helm, wreath, crest, cap, crown, mantling, badge, scroll, etc.

Accessory. One concerned in a crime without directly participating in the commission thereof. An accessory before the fact is a person who instigates another to commit a felony which is committed as the natural and probable consequence of his instigation. An accessory after the fact is a person who, knowing that a felony has been committed, takes active steps to shelter the felon from justice or enable him to escape. Indirect participation in a misdemeanor is not punishable as a crime, and at the common law any participation in treason, however remote, was, on account of the heinousness of the act, punishable as a principal offense. The law has usually provided a different scale of penalties for accessories from those visited upon the principal offenders, but the tendency ofrecent legislation is to abolish the distinction between accessories before the facts and principal.

Acclaccatura, a 'grace-note' played as close as possible before the note which it accompanies, the latter retaining its accent.

Acclaluoli, Donato (1428-78), Italian historian, philosopher, and statesman, gonfalonier of Florence (1473). Wrote Lives of Hannibal, Scipio, and Charlemagne, and Commentaries on Aristotle.

Accidence, that part of grammar which deals with inflections,

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or changes in the form of words produced by the declension of nouns and adjectives or the conjugation of verbs; while syntax deals ^ith the arrangement of words in a sentence.

Accident. Strictly speaking, in law, an occurrence Which results in injury to person or property without legal fault on the part of anyone, as the falling of a tree upon a passer by in consequence of a storm, the bursting of a dam by a flood, resulting in destruction of life, etc. Primitive systems of law punish those responsible for accidental injury to life or limb, however innocent of any wrong they may be, by a forfeiture of the thing (as the fallen tree, the runaway horse, the broken shaft) by or through which the injury was sustained. See Df.odand. In modern law there is no liability without wrongful act or omission on the part of the person charged, though the tendency in recent legislation to charge upon an employer in manufacturing or mining enterprises the loss through injury sustained by his employee while in his service, irrespective of any negligence on the employer's part, is in effect to restore the principle of liability for accident. Analogous to this case is the wellrecognized liability of the innkeeper and common carrier for accidental loss of or injury to property intrusted to him by his guest or shipper. See Employer's Liability; Negligence; Tort.

Accident. In logic, accident signifies a predicate which neither is contained in nor can be inferred from the definition of its subject—• e.g. the predicate black as applied to the subject crow. If all crows without exception were black, blackness would be an 'inseparable accident' of the subject crow, but otherwise it is a 'separable accident.' See also Substance.

Accidentals, signs in musical score which raise (sharp £, double sharp I) or lower (flat b, double flat ]>W the notes beside which they are placed to the extent of one or two semitones, or revoke previous sharps or flats (natural tl). They affect only the bar in which they occur.

Accident Insurance. See InSurance.

Acclimatization. All organisms are as capable of physiological as of morpnologicaf variation; and if the climatic conditions change slowly, they can adjust themselves to these, and become acclimatized. This acclimatization has been very extensively Sractised by man, as in the case of omcstic animals, none of which (save such half-domestic forms as elephants) seem to have originated in the countries where they have been most highly developed. A

Acclimatization

similar record belongs to many useful plants, especially the cereals, which nave nourished best in new regions, but it also occurs r.-ithout his aid. There is soi,ie doubt as to the effect of a mere change of temperature upon organisms, but it seems certain that in the majority of cases transference from an equable climate to-one in which there is a great annual range of temperature is rapidly fatal. Thus, many plants from S. Europe will live out of doors in the mild uniform climate of the west coast of England, but will not live in localities on the Continent where the mean annual temperature is the same, but where the extremes of heat and cold are greater.

In general, the plants and animals which are most readily acclimatized to new conditions are those in which the reproductive period is prolonged. Such forms often show an enormous increase of fertility when transferred to a new and more favorable climate. The rabbit, which has become a pest in Australia and New Zealand, is an illustration of this-but as in the parallel cases of the English sparrow in America, and white clover, together with many other European plants, in New Zealand, the extraordinary abundance of the introduced form is in part to be ascribed to the absence in the new country of the natural checks to increase present in the original home. The abnormal increase of the rabbit in Australia is sometimes given as a proof that the marsupial fauna of that islandcontinent could not have persisted if isolation had not saved it from the competition of the higher mammals; but such facts as the extraordinary spread of Canadian water-weed (A nacharis] through the British Isles, show that even in countries in which the struggle for existence has been keen, vacant places in nature may still remain which can be seized by a dominant foreign species. American zoologists have found that European earthworms have become naturalized in many parts of the United States, and are often much more abundant than the native species.

Associated with the fact of the frequent great fertility of an introduced species is the fact that a parasitic or semi-parasitic form often inflicts far greater injury on its host in a new country than in the old. Thus, the vine phylloxera, introduced into Europe from America, has worked fearful havoc in vineyards in the former continent, while it produced relatively little injury in its native habitat. A study of the U. S. Agricultural Department publications will similarly show that insects, relatively harmless in Europe, have almost paralyzed agriculture when introduced into the United States. Accolade

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The risk of more harm than good resulting from introducing a foreign animal has been proved so great by -xperience with the mongoose in Jamaica, and In other cases, that wise men art now extremely chary of takl.if* to another country even animals known to be beneficial in their own.

Again, a great obstacle to the colonization of various parts of the world by the white man is his liability to parasitic diseases to which the natives are almost or entirely immune, notably malaria —a disease due to the introduction of a protozoon parasite into the blood by the mosquito. On the other hand, the advent of the white man has often resulted in the sweeping away of native races, owing to the introduction of microorganisms to whose action the white is at least partially immune, while the native races are singularly susceptible to it—e.g. smallpox among the Indians. These facts show that organisms are adapted to their surroundings, not only by their structure, but also by functional peculiarities which are equally real, but are incapable of exact description. These functional peculiarities are hereditary, but in the case of dominant stocks, at least, are capable of slow, cumulative modification, so that the descendants may ultimately become habituated to surroundings which would have been at once fatal to the original stock. Acclimatization is thus a proof of the occurrence of physiological variation in organisms. Darwin's Animals and Plants under Domestication (1868) is the great storehouse of information on the subject. See also Hann's Handbuch der Kitmatologie (1897).

Accolade. (1.) The ceremony by which knighthood is conferred; formerly an embrace round the neck, now the touch of a sword on the shoulder. (2.) In musical score, the brace connecting the staves.

Accommodation, a term used in Biblical exegesis to denote the adaptation of absolute truth either (a) by a formal change of method to assist its acceptance, or (b) by a material change to adapt it to altered conditions or contemporary modes of thinking.

Accommodation Bill. Sec Bills And Notes.

Accommodation of Vision, the muscular adaptations of the eye to focus objects at various distances, and in varying degrees of light and darkness.

Accompaniment, a musical term designating the subordinate instrumental parts which accompany the principal voice or instrument, as the pianoforte part in a song, or the orchestral part in a concert. It has every degree of importance and complexity, from

that of a simple 'background' which is quits unessential to the leading, melody, and may even be omitted (ad libitum), to that of an organic part of the composition having a large share in the development of the melodic scheme.

Accomplice. A person associated with one or more others in the commission of a crime. Though punishable like his associates, either as principal or accessory, an accomplice is a competent witness in civil or criminal proceedings against his criminal associates. His testimony, because usually given under a promise or in the expectation of immunity, is regarded with suspicion and is not deemed sufficient in criminal cases to secure conviction without corroboration.

Accord and Satisfaction. A discharge of a contract obligation by a new agreement to that effect. In order to have the effect of a discharge the new agreement must constitute an independent contract based upon a pood consideration, and the consideration must have been paid or performed. It is this performance or 'satisfaction' which makes the 'accord' effective and takes the case out from the operation of the rule that a debt is not discharged by an agreement to forgive it, even though the promise be based on part payment. The contrary doctrine that a receipt in full is a valid discharge of a debt though a departure from the common law, has been adopted in a few states by statute and in one (Connecticut) by judicial decision. With these exceptions the general rule stated above is rigorously maintained in the United States. See Release.

Accordion, a portable musical instrument, with keyboard and mechanical contrivance for wind, invented by Damian at Vienna in 1829. Each key gives two notes, one in expanding, the other in compressing the bellows. The right hand manipulates the keyboard, while the left works the bellows, on the lower side of which are usually found two keys which furnish a simple harmony, generally of the tonic and dominant. The instrument is of no artistic value.

A re on n(. A memorandum setting forth in detail the items of debit and credit existing between the person rendering the account and the person to whom it is rendered. An account may be rendered under a great variety of circumstances and is legally demandable in actions at law based upon a series of transactions and in all cases involving a fiduciary relation, as between principal and agent, trustee and beneficiary, executor and creditor or legatee, assignee in bankruptcy and creditors of the bankrupt and in the dis

Accretlon

solution of partnerships and the winding up of companies. Private corporations as well as public officials and other persons acting in a fiduciary capacity are generally required by law to keep accurate books of account. A current account may be legally closed by rendering it to the party indebted and by its acceptance by the latter. It then becomes an 'account stated' and the balance may thereafter be sued for without proving the items upon which it is based, though it may be impeached for fraud or mutual mistake. An accounting could be had at common law through the form of action known as an action of account, but the cumbersome character of the proceeding has caused it to be generally superseded both in England and the United States by a proceeding in Equity instituted by Bill of Account. See Bookkeeping.

Accountant, a person skilled in the keeping of books of account and in financial matters generally. In England, insurance offices, banks, railway companies, and large mercantile firms employ an official called the accountant, whose duties include oversight of the bookkeepers' and cashiers1 work, preparation of statements, balance-sheets, profit and loss accounts, etc. In the U. S. the term is more loosely applied to any one who keeps books of account, and it is not customary to attach expert accountants permanently to a single business. The expert accountant is temporarily engaged to disentangle accounts of special complexitv, to report periodically on the affairs of large business enterprises, to determine impartially the accuracy of accounts m question or to give expert testimony in matters under litigation.

Account Current, a periodical statement of the debit and credit transactions between parties, in order of date; usually made up in such a form as to show the interest charged or allowed on each item at the date of rendering.

Account Sales, a statement sent by an agent or a broker to the consignor of goods when sold, giving particulars of weight, price obtained, etc., and showing the net proceeds after deduction of expenses.

Accra, scant., W. Africa, cap. of British colony of Gold Coast. Exports gold dust, gum, palm oil, ivory, timber, and rubber. A technical school has been established. Pop. 1.5,000.

Accresclmento, in music, the prolongation of a note for another half of its value, by a dot placed after it.

Accretion. The addition made to riparian land by the gradual action of the water. Such addition, if imperceptible in its progAccrlngton

ress, becomes the property of the owner of the lana to which it is added, whether it be due to alluvion, the deposit of sand and soil by the action of the tides, the washing of waves or the current of a stream, or by reliction, the gradual withdrawal or drying up of a watercourse. For the eorresponding principle in the law of personal property, see Accession. Accrington (anc. Aktrington), England, a munic. bor., Lancashire, 23 m. N. of Manchester. Cotton-spinning, weaving, calicoprinting, and manufacture of textile machinery In the district are coal mines and quarries. Pop. (1901) 43.095.

Accumulations. Funds accruing from time to time under a trust created for the purpose of increasing the principal fund through the periodical addition of the income thereof. The validity of provisions for accumulation are primarily determined by the rule against perpetuities, which restricts the vesting of future interests in property to the period of lives in being and twenty-one years. But the policy of the [aw is unfavorable to accumulations for long periods of time and the rule governing such trusts has consequently been changed so as to limit the period usually to twentyone years. This was effected in England by the Thellusson Act, passed in 1800, and in the several United States by similar statutes. Accumulator, Heat, has for its purpose the accumulation of heat delivered continuously so that it may be expended during short intervals, or, on the other hand, the storing of heat delivered intermittently so that it may be available for continuous use. In engineering practice the heat storing medium is usually water which is not only generally available, but has the highest specific heat per unit of weight of all common substances, and readily transfers its heat to or absorbs it from steam by evaporation or condensation of the latter.

An example of accumulators of the first class is found in special heat storage boilers adapted to receive steam at high pressure from steam boilers operated continuously and then to give off steam during short periods of great demand, as during the rush hours in electric traction power plants. The steam pressure carried in the accumulator, which is simply a large and strong steel tank, must be considerably higher than the working power of the engines, as it is only oy allowing the pressure and therefore the temperature of ihe mass of water in the heat storage tank to fall that the latter is able to supply heat and steam. For instance, if the working pressure of the engines is 150 pounds

per sq. in., corresponding to a steam temperature of 365.6° F., the maximum pressure in the accumulators may be 300 pounds per sq. in., corresponding to a temperature of 421.8° F. During the period of withdrawal, steam will Dc allowed to flow from the storage tanks through a pressure reducing valve and each one hundred pounds of water in the storage tank will be capable of giving up 56 heat units in cooling 421.8s to 365.6° F., and further of evaporating .07 Ib. of steam. During the period of charging the boilers arc in free communication with the accumulator, but during the period of discharge of the accumulator the boilers supply steam directly to the engines. This class of heat accumulator has found only limited application, chiefly in Europe. The advantages claimed for it are that it enables a large maximum load to be carried by a moderate-sized equipment of boilers, and that it permits the boilers to be operated at a uniform and efficient rating throughout the dav. The obvious disadvantage is the extra cost of apparatus, which might conceivably overbalance the advantages. The other type of heat accumulator, in which heat from an intermittent source is stored for continuous use, is found in lowpressure steam turbine practice. Take for instance, steel mills, where large volumes of steam are exhausted at irregular intervals by powerful engines used for driving the rolls or in collcries where the same is true of the winding engines. A steam turbine receiving this steam from the engines at atmospheric pressure and exhausting into a high vacuum produced by a condenser will generate, roughly, about as much more power as has already been produced in the main engine. As steam turbines are, as a rule, employed to drive electric generators and must run constantly, it therefore becomes necessary to store the steam and heat exhausted by the main engine. This is accom

Elished by the following methods: rst, by directing the exhaust steam into large chambers or tanks filled with scrap iron, as old rails, etc.; second, by directing the steam into a chamber filled with a multitude of small trays, each containing water; third, by blowing the exhaust steam in under the surface of water contained in suitable closed lanksj fourth, by directing the steam into a tank above a large body of water, and by mechanical m'eans, throwing the water up into the steam. In all four methods, as will be noted, the object aimed at is to bring the exhaust steam into intimate contact with the whole mass of water or other material which is to store

Accumulators

the heat. If the steam be directed merely into a closed tank above the water, it will be effective in heating only the upper surface of water. In order to prevent dangerous accumulations of pressure in the heat accumulator, a direct connection to the atmosphere is usually provided through a "back

Eressure" valve. On the other and to supply steam continuously to the turbine in case the main engine should be shut off for an exceptionally long time, a pressurereducing valve admitting live steam from the boilers is necessary. Supposing the back pressure valve ue set to open at ten pounds above atmospheric pressure and the reducing valve to begin admitting live steam at three pounds below atmospheric pressure, we have a total pressure range of thirteen pounds and a temperature range of 3S° F. Under these conditions one pound of water in the accumulator is capable of condensing .04 pound of exhaust steam, thereby storing 29 heat units, and of giving up equal quantities of steam and neat when the pressure falls again.

Accumulator, Hydraulic, devised by Lord Armstrong, receives power at a constant rate from a hydraulic pump, and gives it out in large quantities at a time to machines, such as cranes, which work intermittently. It is thus a means of obtaining a considerable volume of water under a high head. It consists of a vertical cylinder with a heavily-weighted ram. See Barr's Pumping Afachincry; and Hydraulic MaChinery.

Accumulators, Electric, or Secondary Batteriks. When an electric battery is discharged, there occur chemical changes in the liquids and electrodes, caused by the passage of the currents through the cell. In some forms of cell all the products of the charge remain in the cell, and the passage of a current in the reverse direction will produce the reverse action and restore the original conditions. Broadly speaking, the current causes a transference of oxygen to one pole and hydrogen to the other, both being "brought back to their previous positions and combinations by the reverse current. Such a battery acts as a reservoir or accumulator of electric cncrgv; for, after each discharge, electric energy is again stored in it by driving a reverse current through it from some other source of electric energy. In the process of charging, the electric pressure of the cell must be overcome, and the resistance of the cell absorbs additional pressure. On discharging, there is likewise a loss of pressure, due to the resistance of the cell, and the

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conditions the loss is not more than some fivr per cent.

Theory of Cfll.—Though many forms of battery allow of reversal, there are few which are satisfactory. The simple collection of oxygen and hvdrogcn at the poles is impracticable, since they pass off as gases, and the only battery that has proved satisfactory is the lead battery invented by Plant6. In this a plate of pure lead forms the negative and a plate of peroxide of lead the positive electrode, immersed in sulphuric arid and water. On discharging, the lead is converted into sulphate of lead, and the hydrogen conveyed to the positive plate is oxidized by the peroxide of lead. The lower oxide thus formed is attacked by the acid, so that sulphate of lead is produced on both plates, and a part of the acid is removed from the liquid. On reversing the current hydrogen is carried to the negative plate, and reduces the sulphate of lead back to metallic lead, while the oxygen converts the sulphate on

ceeds, and its strength indicates the state of the reservoir.

The action of the cell is similar to that of an ordinary primary battery, but there arc important differences. By the use of lead instead of zinc there is formed the insoluble lead sulphate in place of the soluble zinc sulphate or chloride. Therefore the surface becomes covered with the products of the action on both electrodes, and the interior parts of the plates are rendered useless. Consequently both negative and positive plates are constructed of porous, spongy material, presenting an enormous surface to the acid, and solid metal is used only as a framework or carrier. So long as any portion of unchanged material remains in contact with the acid, the E.m.f. is maintained with very gradual reduction. Fig. 2 shows a typical curve of discharge in which horizontal distances represent ampere hours. The cell is practically discharged at 1.8 volts. On charging Fig. 1, the E.M.F. rises rapidly to nearly

Accumulators

2.1 volts, then more slowly to 2.5 volts.

Construction of Plates.—The essential construction is a framework of lead, or an alloy of lead and antimony, containing spongy material. Many forms of grid arc in use. The negative plate is now usually a thin skeleton of lead forming many small pockets, into which is pressed a paste of lead oxide and sulphuric acid. On reduction by the current, this forms a porous mass of lead. The frame of the positive plate is made more stoutly, since the oxygen produced at the end of every charge corrodes the frame slowly. It may be made by filling pockets or grooves with paste as before, which are then converted into peroxide; or this mav be producecf directly by repeated charging, assisted by oxidizing materials, such as sodium nitrate.

Capacity.—The capacity of a cell is determined by the Quantity of electricity it will deliver, usually reckoned in ampere hours. It depends on the construction and size of the plates; but instead of using very large plates, several of cadi kinil mav be used, with positive and negative placed alternately. All of one kind are connected to a common bar, which forms the terminal of the cell. The capacity is not a constant quantity, for with a large current the acid in the pores of the plate is so rapidly weakened that fresh acid from outside cannot diffuse into the plate sufficiently quickly. Hence the interior portions are not fulhy discharged, unless the cell is given a period of rest.

Arrangement oj Cell.—The alternate positive and negative plates are held about half an inch apart by strips of glass or ebonite, and the whole is clamped together to prevent deformation of the plates. The space allows any loosened material to fall clear to the bottom, and in a large battery some three inches of space are left below the plates for its reception. The acid is specially prepared, free from metals, with a density of 1.2, or one volume of strong acid to five of water. If too strong, the lead is slowly attacked; while if too weak, the F.m.f. of the cell is reduced. At this strength also the resistance of the acid is at a minimum. The plates are usually contained in glass boxes when the size is moderate, but for large central-station cells lead-lined wooden boxes, or boxes of a lead alloy, are used. Ebonite boxes are employed for the cells of automobile vehicles on account of lightness, while small portable batteries are generally put in leadlined wood or ebonite with wooden case. The boxes are supported on glass or porcelain feet, to insulate them from the ground, and these

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