C.(a) Abbreviation for Centigrade, as 100 C., meaning 100 Centigrade. (SeeCentigrade Scale.)(b) A symbol of current or of current strength. Thus in the expressionof Ohm's law C = E/R. C indicates current strength or intensity, not inany fixed unit, but only in a unit of the same order in which E and Rare expressed; E Indicating electro-motive force and R resistance.Cable.(a) Abbreviation for Cablegram, q. v.(b) v. It is also used as a verb, meaning to transmit a message bysubmarine cable.(c). An insulated electric conductor, of large diameter. It often isprotected by armor or metallic sheathing and may be designed for use asan aerial, submarine, subterranean or conduit cable. A cable oftencontains a large number of separately insulated conductors, so as tosupply a large number of circuits.Cable, Aerial.A cable usually containing a large number of separately insulated wires,and itself insulated. It is suspended in the air. As its weight issometimes so great that it could not well sustain it, a suspending wireis in such cases carried along with it, to which it is suspended bycable hangers, q. v.Cable Box.A box for receiving underground cable ends and connecting the separatewires of the cable to air-line wires. It is often mounted on a pole,which forms the starting point of the air-line portion of the system.Cable, Bunched.A cable containing a number of separate and individual conductors. Insome forms it consists virtually of two or more small cables laidtangent to each other and there secured. Thus each in section representstwo or more tangent circles with the interstice solidly filled with themetal sheathing.Cable, Capacity of.The electrostatic capacity of a cable. A cable represents a Leyden jaror static condenser. The outer sheathing or armor, or even the more orless moist coating, if it is unarmored, represents one coating. The wireconductors represent the other coating, and the insulator is thedielectric.The capacity of a cable interferes with its efficiency as a conductor ofbroken or interrupted currents, such as are used in telegraphy ortelephoning. As each impulse or momentary current is sent into the line,it has to charge the cable to at least a certain extent before theeffects of the current are perceptible at the other end. Then the cablehas to discharge itself. All this creates a drag or retardation.The capacity of a cable is used to determine the locality of breaks inthe continuity of the conductors. The capacity per unit of length beingaccurately known, it is obvious that, if the conductor breaks withoutdisturbance of the insulator, the distance of the break from the end canbe ascertained by determining the capacity of the cable from one end.This capacity will be in proportion to the capacity of a mile, a knot orany fixed unit, as the distance to the break is to the length used asstandard.96 STANDARD ELECTRICAL DICTIONARY.Cable Core.The conductors of a cable. They are generally copper wire. In atelephone cable they may be very numerous and insulated from each other.In ocean cables they may be a group of bare wires twisted or laidtogether. Sometimes the conductors are arranged for metallic circuits,each pair being distinguished by special colored windings.Cable, Duplex.A cable containing two wires, each with separate insulation, so as to bevirtually two cables, laid and secured parallel and side by side.Cable, Flat.A cable, flat in shape, so as to lie closely against a wall or ceiling.Cablegram.A message which has been transmitted or is to be transmitted by asubmarine cable. It is sometimes called a cable.Cable Grip.A grip for holding the end of a cable, when the cable is to be drawninto a conduit in a subway. It is an attachment to provide the cablewith an eye or loop. Its end is a split socket and embraces the end ofthe cable, and is secured thereto by bolts driven through the cable end.In drawing a cable into a conduit a capstan and rope are often used, andthe rope is secured to the cable end by the grip.Fig. 73. CABLE HANGER, CABLE, AND SUSPENDING WIRE.Fig. 74. CABLE HANGER, OPEN.Cable Hanger.When a heavy electric cable is suspended from poles it often would beunsafe to trust to its longitudinal strength to support or sustain itsown weight unless the poles were very near together. In such case anauxiliary or sustaining wire is run along with it, and by clips orhangers the cable is connected thereto at as frequent intervals as seemdesirable. The contrivance may take the form of a strip of metalsurrounding the cable and carrying a hook or eye through which thesupporting wire passes.Synonym--Cable Clip.97 STANDARD ELECTRICAL DICTIONARYCable Hanger Tongs.Tongs for attaching cable hangers, q.v. They have long handles so as tobe worked from the ground at the middle of a span.Cable, Suspending Wire of.A wire by which an aerial cable is in part or entirely suspended. Thecable, being incapable of sustaining its own weight, is secured by clipsor hangers to a wire, strong from pole to pole immediately above it.(See Cable Hanger.)Cable Tank.A tank in which a submarine cable is coiled away on board a cable-layingship, or in the factory on shore for the purpose of testing orwatching its insulation. Sometimes, in order to test it under pressuresapproximating to those it will be subjected to in practice, the tank isclosed and the portion of cable within it is subjected to hydraulicpressure. This represents the pressure it will be exposed to in deepwater.Calamine.A mineral; zinc silicate; formula Zn2 Si 03, crystalline system,Orthorhombic; specific gravity, 3.16-3.9.The crystals often show strong pyroelectric properties.Calibration.The determination by experiment or calculation of the value of thereadings of an instrument, such as a galvanometer or eudiometer. Thus ifa tangent galvanometer has its circle graduated in degrees, a table ofthe value of tangents corresponding to every reading occurring inpractice would represent a calibration by calculation. A determinationof the current required to produce each deflection would be acalibration in the more usual sense. Calibration is generally absolute,as referring to some fixed unit, but it may be relative, as between twothings both of unknown absolute value.Calibration, Absolute.The determination of the absolute value of currents producing givendeflections in a galvanometer, or in other instruments the determinationof corresponding values, as the instrument may be a magnetometer,quadrant electrometer, or other apparatus.Calibration, Invariable.Calibration applicable to specially constructed galvanometers, which isunaffected by the proximity of masses of iron or field magnets. Suchgalvanometers must have a constant controlling field. Such is given by apowerful permanent magnet, whose field is practically unaffected by thecauses named. Or else, in place of a controlling field, a spring maybeused to which the needle is attached, and which tends to hold it in oneposition.98 STANDARD ELECTRICAL DICTIONARY.Calibration, Relative.The determination of the law connecting the various indications of aninstrument, such as the deflections of the needle of a galvanometer,with the relative causes; in the case of a galvanometer, the strength ofthe currents or the electro-motive forces producing them directly orindirectly.Call Bell.A bell rung by pressing a button or otherwise to call the attention of aperson in a distant place. They can be classified into a great varietyof types according to their uses or construction.Call Button.A push button used for ringing a call bell, sounding a buzzer, workingan annunciator and for similar purposes. (See Push Button.)Synonym--Push Button.Calling Drop.In a telephone exchange or telegraph office a drop shutter annunciator,which falls to call the attention of the operator, notifying him thatthe line connected to such drop is to be connected to some othercircuit.Calorie or Calory.A practical unit of heat. There are two calories, respectively calledthe great and the small calorie, or the kilogram and the gram calorie.The first is the quantity of heat required to raise the temperature ofone kilogram of water one degree centigrade. The second is the quantityof heat required to raise the temperature of one gram of water onedegree centigrade.Calorimeter.An apparatus for measuring the quantity of heat evolved or produced byor under different conditions. Dulong's water calorimeter consists of awater jacket, and by the increase of temperature of the water andenclosing vessels the amount of heat produced by anything in the innervessels is determined. The amount of ice a heated body will melt issometimes made the basis of a calorimeter. The expansion of a fluid, aswater, may be used. In the calorimeter shown in the cut the heatproduced in a conductor by the passage of an electric current is causedto heat water whose temperature is shown by a thermometer immersedtherein. The increase of temperature and the weight of the water givethe basis for a determination of the heat produced by the current.Knowing the resistance of the conductor immersed, the watts can becalculated. This gives the bases for the determination of theheat-equivalent of electric energy. This is but an imperfectcalorimeter, as it constantly would lose heat by the surroundingatmosphere, and would cease to operate as a calorimeter when the waterwas as hot as the wire normally would be, for then it would not absorball the heat.Fig. 75. CALORIMETER.99 STANDARD ELECTRICAL DICTIONARY.Candle.The generally accepted unit of illuminating power; there arethree kinds in use as standards. (See Candle, Decimal--Candle, GermanStandard--Candle, Standard.)Candle, Concentric.An electric candle of the Jablochkoff type, having a small solid carboninside of an outside tubular carbon, the space between being filled withrefractory material corresponding to the colombin, q. v., of theordinary type. The arc springs across from one carbon to the other.Candle, Debrun.An arc lamp with approximately parallel carbons. A transverse primingconnects their bases, and the arc starting there at once flies out tothe end.Candle, Decimal.A standard of illuminating power, proposed to the Congress ofElectricians of 1889 by Picou. It is one-twentieth of a Viole, or almostexactly one standard candle. (See Viole's Standard of IlluminatingPower.)Candle, Electric.An arc lamp regulated by simple gravity, or without any feed of thecarbons or special feeding apparatus, generally for the production of anarc light of low intensity. This definition may be considered tooelastic, and the word may be restricted to parallel carbon lamps inwhich the arc springs across from carbon to carbon. For the latter classan alternating current is used to keep the carbons of equal length. Theyare but little used now. Various kinds have been invented, some of whichare given here.Candle, German Standard.A standard of illuminating power used in Germany. It is a paraffincandle, 6 to the pound, 20 millimeters diameter; flame, 56 millimetershigh; rate of consumption, 7.7 grams per hour. Its value is about twoper cent. lower than the English standard candle.100 STANDARD ELECTRICAL DICTIONARY.Candle Holder.A clamp for holding electric candles of the Jablochkoff type. The onesshown in the cut designed for Jablochkoff candles comprise a pair ofmetallic clamps, each member insulated from the other, and connected asterminals of the circuit. When the candle is placed in position themetal pieces press against the carbons of the candle and thus convey thecurrent. Below each member of the clamps is a binding screw for the linewire terminals.Fig. 76. JABLOCHKOFF CANDLE HOLDERS.Fig. 77. JABLOCHKOFF CANDLE.Candle, Jablochkoff.An arc lamp without regulating mechanism, producing an arc between theends of parallel carbons. It consists of two parallel rods of carbon,between which is an insulating layer of non-combustible material calledthe colombin. Kaolin was originally employed for this part; later, asthe fusion of this material was found to short- circuit the arc, amixture of two parts of calcium sulphate and one of barium sulphate wasused. The carbons are 4 millimeters (.16 inch) thick, and the colombinis 3 millimeters (.12 inch) wide and two-thirds as thick. A little slipof carbon is placed across the top, touching both carbons to start thearc. Once started the candle burns to the end, and cannot be restartedafter ignition, except by placing a short conductor across the ends, asat first. The Jablochkoff candle may now be considered as virtuallyextinct in this country. In France at one time a great number were inuse.To keep the carbons of equal length an alternating current must alwaysbe used with them. Special alternating combinations were employed insome cases where a direct current had to be drawn upon.Candle, Jamin.An arc lamp with approximately parallel carbons, one of which oscillatesand is controlled by an electro-magnet and armature. A coil of wire iscarried around the carbons to keep the arc steady and in place. Theframe and wire coils have been found unsatisfactory, as causing ashadow.Candle Power.The amount of light given by the standard candle. The legal English andstandard American candle is a sperm candle burning two grains a minute.It should have burned some ten minutes before use, and the wick shouldbe bent over and have a red tip. Otherwise its readings or indicationsare useless. A sixteen candle power lamp means a lamp giving the lightof sixteen candles. The candle power is a universal unit of illuminatingpower.101 STANDARD ELECTRICAL DICTIONARY.Candle Power, Rated.The candle power of arc lamps is always stated in excess of the truth,and this may be termed as above. A 2000 candle power lamp really givesabout 800 candles illumination.Synonym--Nominal Candle Power.Candle Power, Spherical.The average candle power of a source of light in all directions. An arclamp and an incandescent lamp vary greatly in the intensity of lightemitted by them in different directions. The average of a number ofdeterminations at various angles, the lamp being moved about intodifferent positions, is taken for the spherical candle power.Candle, Standard.A standard of illuminating power. Unless otherwise expressed the Englishstandard sperm candle is indicated by this term. (See Candle Power.)Candle, Wilde.An arc lamp with approximately parallel carbons. One of the carbons canrotate through a small arc being pivoted at its base. This oscillationis regulated by an electro-magnet at its base, and the carbons touchwhen no current is passing. They separate a little when the currentpasses, establishing an arc. The regulation is comparable to that of aregular arc lamp.Fig. 78. WILDE CANDLE.Caoutchouc.India rubber; a substance existing in an emulsion or solution in thejuice of certain trees and vines of the tropics, whence it is obtainedby coagulation and drying. The name "rubber" is due to the fact that oneof its earliest uses was for erasing pencil marks by rubbing. It has avery high value as an insulator. The unworked crude rubber is calledvirgin gum; after working over by kneading, it is termed masticated orpure gum rubber; after mixture with sulphur and heating, it is termedvulcanized rubber. If enough sulphur is added it becomes hard, and ifblack, is termed ebonite; if vermilion or other pigment is also added toproduce a reddish color, it is termed vulcanite. The masticated gumdissolves more or less completely in naphtha (sp. gr., .850) benzole,turpentine, chloroform, ether and other similar liquids.. The resistanceper centimeter cube of "Hooper's" vulcanized India rubber, such as isused in submarine cables is 1.5E16 ohms. The specific inductive capacityof pure India rubber is 2.34--of vulcanized 2.94 (Schiller).Synonyms--India Rubber--Rubber.102 STANDARD ELECTRICAL DICTIONARY.Capacity, Dielectric.The capacity of a dielectric in retaining an electrostatic charge; thesame as Specific Inductive Capacity. 'The number expressing it issometimes called the dielectric constant. (See Capacity, SpecificInductive.)Capacity, Electric, or Electrostatic.The relative capacity of a conductor or system to retain a charge ofelectricity with the production of a given difference of potential. Thegreater the charge for a given change of potential, or the less thechange of potential for a given charge the greater the capacity. Themeasure of its capacity is the amount of electricity required to raisethe potential to a stated amount. The unit of capacity is the farad, q.v. Electric capacity is comparable to the capacity of a bottle for air.A given amount of air will raise the pressure more or less, and theamount required to raise its pressure a stated amount might be taken asthe measure of capacity, and would be strictly comparable toelectrostatic charge and potential change. The capacity, K, is obviouslyproportional to the quantity, Q, of the charge at a given potential, E,and inversely proportional to the potential, E, for a given quantity, Q,or,(1) K == Q/Eand(2) Q = K * E,or, the quantity required to raise a conductor by a given potential isequal to the capacity of the conductor or system multiplied by the riseof potential. The capacity of a conductor depends upon its environments,such as the nature of the dielectric surrounding it, the proximity ofoppositely charged bodies and other similar factors. (SeeDielectric-Condenser-Leyden jar.)The dimensions of capacity are found by dividing a quantity ofelectricity by the potential produced in the conductor by suchquantity.Quantity ( ((M^.5)*(L^1.5)) / T ) / potential ( ((M^.5)*(L^.5)) / T ) = L.Capacity, Instantaneous.The capacity of a condenser when connected only for an instant to asource of electricity. This is in contrast to electric absorption (seeAbsorption, Electric), and is capacity without such absorption takingpart in the action.103 STANDARD ELECTRICAL DICTIONARY.Capacity of a Telegraph Conductor.The electric capacity of a telegraphic conductor is identical in qualitywith that of any other conductor. It varies in quantity, not only fordifferent wires, but for the same wire under different environments, asthe wire reacting through the surrounding air or other dielectric uponthe earth, represents one element of a condenser, the earth, in general,representing the other. Hence, a wire placed near the earth has greatercapacity than one strung upon high poles, although the wires may beidentical in length, material and diameter. The effect of high capacityis to retard the transmission of intermitting signals. Thus, when--as inthe Morse system--a key is depressed, closing a long telegraph currentand sending a signal into a line, it is at least very probable that aportion of the electricity travels to the end of the wire with thevelocity of light. But as the wire has to be charged, enough current tomove the relay may not reach the end for some seconds.Capacity of Polarization of a Voltaic Cell.The relative resistance to polarization of a voltaic cell, measured bythe quantity of electricity it can supply before polarization. Acounter-electromotive force may be developed, or the acid or othersolution may become exhausted. The quantity of electricity deliveredbefore this happens depends on the size and type of cell and otherfactors.Capacity, Residual.When two insulated conductors are separated by a dielectric, and aredischarged disruptively by being connected or nearly connectedelectrically, on removing the discharger it is found that a slightcharge is present after a short interval. This is the residual charge.(See Charge, Residual.) Shaking or jarring the dielectric facilitatesthe complete discharge. This retaining of a charge is a phenomenon ofthe dielectric, and as such, is termed residual capacity. It variesgreatly in different substances. In quartz it is one-ninth what it is inair. Iceland spar (crystalline calcite) seems to have no residualcapacity. The action of shaking and jarring in facilitating a dischargeindicates a mechanical stress into which the electrostatic polarizationof the conductor has thrown the intervening dielectric.Capacity, Specific Inductive.The ratio of the capacity of a condenser when its plates are separatedby any substance to the capacity of the same condenser when its platesare separated by air.A static accumulator consists of two conducting surfaces separated by aninsulator. It is found that the capacity of an accumulator for anelectric charge, which varies with or may be rated by the potentialdifference to which its conductors will be brought by the given charge,varies with the nature of the interposed dielectric, and is proportionalto a constant special to each substance. This constant is the specificinductive capacity of the dielectric.The same condenser will have a higher capacity as the dielectric isthinner, other things being equal. But different dielectrics havingdifferent specific inductive capacities, the constant may be determinedby ascertaining the relative thicknesses of layers having the same totalinductive capacity. The thicker the layer, the higher is its specificinductive capacity.Thus it is found that 3.2 units thickness of sulphur have the same totalinductive capacity as 1 unit thickness of air. In other words, ifsulphur is interposed between two conducting plates, they may beseparated to over three times the distance that would be requisite toretain the same capacity in air. Hence, sulphur is the betterdielectric, and air being taken as unity, the specific inductivecapacity of sulphur is 3.2.104 STANDARD ELECTRICAL DICTIONARY.The specific inductive capacity of a dielectric varies with the time andtemperature. That of glass rises 2.5 per cent. between 12° C. (53.6° F.)and 83° C. (181.4° F.). If a condenser is discharged disruptively, itretains a small residual charge which it can part with later. If ametallic connection is made between the plates, the discharge is notinstantaneous. Vibration shaking and jarring facilitate the completedischarge. All this shows that the charge is a phase of the dielectricitself, and indicates a strained state into which it is brought.The following table gives the specific inductive capacity of varioussubstances:Specific Inductive Capacity.Substance SpecificInductive AuthorityCapacity.Vacuum, air at about 0.001 millimeters pressure 0.94 about AyrtonVacuum, air at about 5 millimeters 0.9985 Ayrton0.99941 BoltzmannHydrogen at about 760 millimeters pressure 0.9997 Boltzmann0.9998 AyrtonAir at about 760 millimeters pressure 1.0 Taken as thestandardCarbon Dioxide at about 760 millimeters pressure 1.000356 Boltzmann1.0008 AyrtonOlefiant Gas at about 760 millimeters pressure 1.000722 BoltzmannSulphur Dioxide at about 760 millimeters pressure 1.0037 AyrtonParaffin Wax, Clear 1.92 Schiller1.96 Wüllner1.977 Gibson and Barclay2.32 BoltzmannParaffin Wax, Milky 2.47 SchillerIndia Rubber, Pure 2.34 SchillerIndia Rubber, Vulcanized 2.94 SchillerResin 2.55 BoltzmannEbonite 2.56 Wüllner2.76 Schiller3.15 BoltzmannSulphur 2.88 to 3.21 Wüllner3.84 BoltzmannShellac 2.95 to 3.73 WüllnerGutta percha 4.2Mica 5Flint Glass, Very light 6.57 J. HopkinsonFlint Glass, Light 6.85 J. HopkinsonFlint Glass, Dense 7.4 J. HopkinsonFlint Glass, Double extra dense 10.1 J. Hopkinson105 STANDARD ELECTRICAL DICTIONARY.Capacity, Unit of.The unit of capacity is the capacity of a surface which a unit quantitywill raise to a unit potential. The practical unit is the surface whicha coulomb will raise to one volt, and is called the farad, q. v.Capacity, Storage.In secondary batteries the quantity of electrical current which they cansupply when charged, without undue exhaustion. It is expressed inampere-hours. The potential varies so little during the discharge thatit is assumed to be constant.Capillarity.The reaction between liquid surfaces of different kinds or betweenliquid and solid surfaces due to surface tension. Its phenomena aregreatly modified by electric charging, which alters the surface tension.Capillarity is the cause of solutions "creeping," as it is termed. Thusin gravity batteries a crust of zinc sulphate often formed over the edgeof the jar due to the solution creeping and evaporating. As a liquidwithdraws from a surface which it does not wet, creeping as above isprevented by coating the edge with paraffin wax, something which waterdoes not moisten. It also causes the liquids of a battery cell to reachthe connections and injure them by oxidation. The solutions creep up inthe pores of the carbons of a battery and oxidize the clamps. To givegood connections a disc of platinum or of lead is used for the contactas not being attacked. Another way is to dip the upper ends of the dryand warm carbons into melted paraffin wax, or to apply the wax to thehot carbons at the top, and melt it in with a hot iron.106 STANDARD ELECTRICAL DICTIONARY.Carbon.(a) One of the elements; atomic weight, 12. It exists in threeallotropic modifications, charcoal, graphite and diamond. In thegraphitic form it is used as an electric current conductor, as inbatteries and for arc lamp, electrodes and incandescent lamp filaments.It is the only substance which conducts electricity and which cannot bemelted with comparative ease by increase of current. (See Resistance.)(b) The carbon plate of a battery or rod of an arc lamp. To securegreater conductivity in lamp carbons, they are sometimes plated withnickel or with copper.(c) v. To place carbons in arc lamps. This has generally to be done oncein twenty-four hours, unless the period of burning is very short.Carbon, Artificial.For lamps, carbons and battery plates carbons are made by igniting,while protected from the action of the air, a mixture of carbon dust anda cementing and carbonizable substance. Lamp black may be added also.Powdered coke or gas carbon is mixed with molasses, coal tar, syrup, orsome similar carbonaceous liquid. It is moulded into shape. For lampcarbons the mixture is forced from a vessel through a round aperture ordie, by heavy pressure, and is cut into suitable lengths. For batteryplates it may be simply pressed into moulds. The carbons are ignited incovered vessels and also covered with charcoal dust, lamp black or itsequivalent. They are heated to full redness for some hours. Afterremoval and cooling they are sometimes dipped again into the liquid usedfor cementing and reignited. Great care in securing pure carbon issometimes necessary, especially for lamps. Fine bituminous coal issometimes used, originally by Robert Bunsen, in 1838 or 1840;purification by different processes has since been applied; carbon fromdestructive distillation of coal tar has been used. The famous Carrécarbons are made, it is said, from 15 parts very pure coke dust, fiveparts calcined lamp-black, and seven or eight parts sugar--syrup mixedwith a little gum. Five hours heating, with subsequent treatment withboiling caramel and reignition are applied. The latter treatment istermed "nourishing." Napoli used three parts of coke to one of tar.Sometimes a core of different carbon than the surrounding tube isemployed.107 STANDARD ELECTRICAL DICTIONARY.The following are the resistances of Carré's carbons per meter (39.37inches):Diameter in Diameter in Resistance in Ohms.Millimeters. Inches. @ 20° C. (98° F.)1 .039 50.0002 .078 12.53 .117 5.554 .156 3.1255 .195 2.0006 .234 1.3908 .312 .78110 .390 .512 .468 .34815 .585 .22218 .702 .15420 .780 .125At high temperatures the resistance is about one-third these amounts. Alayer of copper may increase the conductivity one hundred times andprolong the duration 14 per cent. Thus a layer of copper 1/695millimeter (1/17300 inch) thick increases the conductivity 4.5 times; acoating 1/60 millimeter (1/1500 inch) thick increases the conductivityone hundred and eleven times.Carbon, Cored.A carbon for arc lamps with a central core of softer carbon than theexterior zone. It fixes the position of the arc, and is supposed to givea steadier light.Synonym--Concentric Carbon.Carbon Holders.In arc lamps, the fixed clamps for holding the ends of the carbons.Carbonization.The igniting in a closed vessel, protected from air, of an organicsubstance so as to expel from it all the constituents except part ofthe carbon; destructive distillation. (See Carbonized Cloth.)Carbonized Cloth.Cloth cut in discs and heated in vessels protected from the air, untilreduced to carbon. The heating is sometimes conducted in vacuo. They areplaced in a pile in a glass or other insulating tube, and offer aresistance which can be varied by pressure. The greater the pressure theless will be the resistance, and vice versa.Carbon Dioxide.A compound gas, CO2. It is composed ofCarbon, 12 parts by weight.Oxygen. 32 "Specific gravity, 1.524 (Dulong and Berzelins).Molecular weight, 44.It is a dielectric of about the resistance of air. Its specificinductive capacity at atmospheric pressures is1.000356 (Boltzmann).1.0008 (Ayrton).Synonyms--Carbonic Acid--Carbonic Acid Gas.108 STANDARD ELECTRICAL DICTIONARYCarbon, Volatilization of.In arc lamps the heat is so intense that it is believed that part of thecarbon is volatilized as vapor before being burned or oxidized by theoxygen of the air. The same volatilization may take place inincandescent lamps which are overheated.Carcel.The standard of artificial illumination used in France. It is the lightyielded by a standard lamp burning 42 grams (648 grains) of colza oilper hour, with a flame 40 millimeters (1.57 inch) in height. One carcelis equal to 9.5 to 9.6 candles.Carcel Lamp.The lamp giving the standard of illuminating power. The wick iscylindrical, giving an Argand or central draft flame. It is woven with75 strands, and weighs 3.6 grams (55.5 grains) per decimeter (3.9inches) of length. The chimney is 29 centimeters (11.3 inches) high, 47millimeters (1.88 inch) in diameter at the bottom, contracting justabove the wick to 34 millimeters (1.36 inch).Carcel Gas Jet.A standard Argand gas burner, made with proper rating to give the lightof a definite number of carcels illuminating power. Cognizance must betaken of the quality of the gas as well as of the burner used.Carrying Capacity.In a current conductor, its capacity for carrying a current withoutbecoming unduly heated. It is expressed in amperes. (See Wire Gauge,American.)Cascade.The arrangement of Leyden jars in series on insulating supports, asdescribed below.Cascade, Charging and Discharging Leyden Jars In.An arrangement of Leyden jars in series for the purpose of charging anddischarging. They are placed on insulating supports, the inner coatingof one connected with the outer coating of the next one all through theseries. The actual charge received by such a series, the outer coatingof one end jar being grounded, and the inner coating of the other beingconnected to a source of high potential, or else the same beingconnected to electrodes of opposite potentials is no greater than thatof a single jar, but a much higher potential difference can be developedwithout risk of perforating the glass of a jar. The difference ofpotential in each jar of the series is equal to the total potentialdifference divided by the number of jars. The energy of discharge isequal to the same fraction of the energy of a single jar charged withthe same quantity.[Transcriber's note: The equal distribution of potential assumes all thejars have the same capacity. The charge on all jars is the same sincethey are in series.]109 STANDARD ELECTRICAL DICTIONARY.Case-hardening, Electric.The conversion of the surface of iron into steel by applying a propercarbonaceous material to it while it is heated by an electric current.It is a superficial cementation process.Cataphoresis.Electric osmore; the transfer of substances in solution through porousmembranes under the influence probably of electrolysis, but withoutthemselves being decomposed.Cautery, Electric.An electro-surgical appliance for removing diseased parts, or arrestinghemorrhages, taking the place of the knife or other cutting instrument.The cautery is a platinum wire heated to whiteness by an electriccurrent, and when in that condition used to cut off tumors, stop theflow of blood and parallel operations. The application is painful, butby the use of anaesthetics pain is avoided, and the healing after theoperation is greatly accelerated.The heated wire of the cautery can be used for cutting operations inmany cases where excision by a knife would be almost impracticable.Synonyms--Galvano-cautery--Galvano-caustry--Galvano-electric,do.--Galvano-thermal, do.C. C.A contraction of cubic centimeter. It is often written in small letters,as 100 c.c., meaning 100 cubic centimeters.Cell, Constant.A cell which yields a constant and uniform current under unvaryingconditions. This implies that neither the electro-motive force or theresistance of the cell shall vary, or else that as the electro-motiveforces run down the resistance shall diminish in proper proportion tomaintain a constant current. There is really no constant cell. Theconstancy is greatest when the external resistance is high in proportionto the internal resistance.Cell, Electrolytic.A vessel containing the electrolyte, a liquid decomposable by thecurrent, and electrodes, arranged for the passage of a decomposingcurrent. The voltameter, q. v., is an example.Cell, Standard Voltaic.A cell designed to be a standard of electro-motive force; one in whichthe same elements shall always be present under the same conditions, soas to develop the same electro-motive force. In use the circuit isclosed only for a very short time, so that it shall not become alteredby polarization or exhaustion.Cell, Standard Voltaic, Daniell's.A zinc-copper-copper sulphate couple.Many forms are used. Sometimes a number of pieces of blotting paper areinterposed between two plates, one of copper--the other of zinc. Thepaper next the copper is soaked in copper sulphate solution, and thosenext the zinc in zinc sulphate solution, of course before being puttogether. Sometimes the ordinary porous cup combination is employed. Thecut shows a modification due to Dr. Fleming (Phil. Mag. S. 5, vol. xx,p. 126), which explains itself. The U tube is 3/4-inch diameter, and 8inches long. Starting with it empty the tap A is opened, and the whole Utube filled with zinc sulphate solution, and the tap A is closed. Thezinc rod usually kept in the tube L is put in place, tightly corking upits end of the U tube. The cock C is opened, which lowers the level ofthe solution in the right-hand limb of the U tube only. The tap B isopened and the copper sulphate solution is run in, preserving the lineof separation of the two solutions. The copper rod is taken out of itstube M, and is put in place. India rubber corks are used for both rods.As the liquids begin to mix the mixture can be drawn off at C and thesharp line of demarcation re-established. In Dr. Sloane's standard celltwo test tubes are employed for the solutions and a syphon is used toconnect them.Oxidation of the zinc lowers the E. M. F.; oxidation of the copperraises it. With solutions of equal sp. gr. the E. M. F. is 1.104 volts.If the copper sulphate solution is 1.100 sp. gr. and the zinc sulphatesolution 1.400 sp. gr., both at 15° C. (59°F.), the E. M. F. will be1.074 volt. Clean pure zinc and freshly electrolyzed copper should beused.Fig. 79 STANDARD DANIELL CELL--FLEMING'S FORM.110 STANDARD ELECTRICAL DICTIONARY.Cell, Standard Voltaic, Latimer Clark's.A mercury and zinc electrode couple withmercurous sulphate as excitant and depolarizer. The positiveelement is an amalgam of zinc, the negative is pure mercury. Eachelement, in a representative form, the H form, is contained in aseparate vessel which communicate by a tube. Over the pure mercury somemercurous sulphate is placed. Both vessels are filled to above the levelof the connecting tube with zinc sulphate solution, and kept saturated.It is tightly closed or corked. The E. M. F. at 15° C (59° F.) is 1.438.Temperature correction(1 - (.00077 *(t - 15° C) ) )t being expressed in degrees centigrade (Rayleigh). A diminution inspecific gravity of the zinc solution increases the E. M. F. The cellpolarizes rapidly and the temperature coefficient is considered toohigh.Fig. 80. LATIMER CLARK'S STANDARD CELL.111 STANDARD ELECTRICAL DICTIONARY.Cements, Electrical.A few cements find their use in electrical work. Marine glue,Chatterton's compound, and sealing wax may be cited.Centi-.Employed as a prefix to indicate one-hundredth, as centimeter, theone-hundredth of a meter; centi-ampere, the one-hundredth of an ampere.Centigrade-scale.A thermometer scale in use by scientists of all countries and in generaluse in many. The temperature of melting ice is 0º; the temperature ofcondensing steam is 100° ; the degrees are all of equal length. Toreduce to Fahrenheit degrees multiply by 9 and divide by 5, and add 32algebraically, treating all readings below 0º as minus quantities. Forits relations to the Reamur scale, see Reamur Scale. Its abbreviation isC., as 10º C., meaning ten degrees centigrade.Centimeter.A metric system unit of length; one-hundredth of a meter; 0.3937 inch.The absolute or c. g. s. unit of length.Centimeter-gram-second System.The accepted fundamental or absolute system of units, called the C. G.S. system. It embraces units of size, weight, time, in mechanics,physics, electricity and other branches. It is also called the absolutesystem of units. It admits of the formation of new units as required byincreased scope or classification. The following are basic units of thesystem :Of length, centimeter;of mass, gram;of time, second:of force, dyne:of work or energy, erg.See Dyne, Erg., and other units in general.112 STANDARD ELECTRICAL DICTIONARY.Central Station Distribution or Supply.The system of supplying electric energy in current form from a maingenerating plant to a district of a number of houses, factories, etc. Itis in contrast with the isolated plant system in which each house orfactory has its own separate generating installment, batteries ordynamos.Centre of Gravity.A point so situated with respect to any particular body, that theresultant of the parallel attracting forces between the earth and theseveral molecules of the body always passes through it. These areresultants of the relative moments of the molecules. If a body issuspended, as by a string, the centre of gravity always lies verticallyunder its point of suspension. By two trials the point of intersectionof plumb lines from the point of suspension being determined the centreof gravity is known. The vertical from the point of support coincideswith the line of direction.Centre of Gyration.The centre of gyration with respect to the axis of a rotating body is apoint at which if the entire mass of the body were concentrated itsmoment of inertia would remain unchanged. The distance of this pointfrom the axis is the radius of gyration.Centre of Oscillation.The point referred to in a body, suspended or mounted to swing like apendulum, at which if all the mass were concentrated, 1t would completeits oscillations in the same time. The distance from the axis of supportto this point gives the virtual length of the pendulum which the bodyrepresents.Centre of Percussion.The point in a suspended body, one free to swing like a pendulum, atwhich an impulse may be applied, perpendicular to the plane through theaxis of the body and through the axis of support without shock to theaxis. It is identical with the centre of oscillation, q. v., when suchlies within the body.Centrifugal Force.The force which draws a body constrained to move in a curved path awayfrom the centre of rotation. It is really due to a tangential impulseand by some physicists is called the centrifugal component of tangentialvelocity. It has to be provided against in generator and motorarmatures, by winding them with wire or bands to prevent the coils ofwire from spreading or leaving their bed upon the core.113 STANDARD ELECTRICAL DICTIONARY.Centrifugal Governor.The usual type of steam-engine governor. The motion of the enginerotates a system of weights, which are forced outward by centrifugalforce, and are drawn inwards by gravity or by springs. Moving outwardsthey shut off steam, and moving inwards they admit it, thus keeping theengine at approximately a constant speed. The connections between themand the steam supply and the general construction vary widely indifferent governors.C. G. S.Abbreviation or symbol for Centimeter-gram-second, as the C. G. S.system. (See Centimeter-gram-second System.) It is sometimes expressedin capitals, as above, and sometimes in small letters, as the c. g. s.unit of resistance.Chamber of Incandescent Lamp.The interior of the bulb of an incandescent lamp. (See Lamp,Incandescent.)Fig. 81. CHARACTERISTIC CURVE OF A DYNAMO.FIG. 82. DROOPING CHARACTERISTIC.Characteristic Curve.A curve indicating the variations in electro-motive force developedduring the rotations of the armature of a dynamo or other generator ofE. M. F. The term as used in the electrical sense is thus applied,although the indicator diagram of a steam engine may be termed itscharacteristic curve, and so in many other cases. As the amperes takenfrom a series generator are increased in number, the E. M. F. rises, itmay be very rapidly up to a certain point, and thereafter more slowly.To construct the curve coordinates, q. v., are employed. The resistanceof the dynamo and of the outer circuit being known, the currentintensity is measured. To obtain variations in electro-motive force theexternal resistance is changed. Thus a number of ampere readings withvarying known resistance are obtained, and for each one anelectro-motive force is calculated by Ohm's law. From these data a curveis plotted, usually with volts laid off on the ordinate and amperes onthe abscissa.