The Standard Electrical Dictionary Part 27

Calorimeter.

An apparatus for measuring the quant.i.ty of heat evolved or produced by or under different conditions. Dulong's water calorimeter consists of a water jacket, and by the increase of temperature of the water and enclosing vessels the amount of heat produced by anything in the inner vessels is determined. The amount of ice a heated body will melt is sometimes made the basis of a calorimeter. The expansion of a fluid, as water, may be used. In the calorimeter shown in the cut the heat produced in a conductor by the pa.s.sage of an electric current is caused to heat water whose temperature is shown by a thermometer immersed therein. The increase of temperature and the weight of the water give the basis for a determination of the heat produced by the current.

Knowing the resistance of the conductor immersed, the watts can be calculated. This gives the bases for the determination of the heat-equivalent of electric energy. This is but an imperfect calorimeter, as it constantly would lose heat by the surrounding atmosphere, and would cease to operate as a calorimeter when the water was as hot as the wire normally would be, for then it would not absorb all the heat.

Fig. 75. CALORIMETER.

99 STANDARD ELECTRICAL DICTIONARY.

Candle.

The generally accepted unit of illuminating power; there are three kinds in use as standards. (See Candle, Decimal--Candle, German Standard--Candle, Standard.)

Candle, Concentric.

An electric candle of the Jablochkoff type, having a small solid carbon inside of an outside tubular carbon, the s.p.a.ce between being filled with refractory material corresponding to the colombin, q. v., of the ordinary type. The arc springs across from one carbon to the other.

Candle, Debrun.

An arc lamp with approximately parallel carbons. A transverse priming connects their bases, and the arc starting there at once flies out to the end.

Candle, Decimal.

A standard of illuminating power, proposed to the Congress of Electricians of 1889 by Picou. It is one-twentieth of a Viole, or almost exactly one standard candle. (See Viole's Standard of Illuminating Power.)

Candle, Electric.

An arc lamp regulated by simple gravity, or without any feed of the carbons or special feeding apparatus, generally for the production of an arc light of low intensity. This definition may be considered too elastic, and the word may be restricted to parallel carbon lamps in which the arc springs across from carbon to carbon. For the latter cla.s.s an alternating current is used to keep the carbons of equal length. They are but little used now. Various kinds have been invented, some of which are given here.

Candle, German Standard.

A standard of illuminating power used in Germany. It is a paraffin candle, 6 to the pound, 20 millimeters diameter; flame, 56 millimeters high; rate of consumption, 7.7 grams per hour. Its value is about two per cent. lower than the English standard candle.

100 STANDARD ELECTRICAL DICTIONARY.

Candle Holder.

A clamp for holding electric candles of the Jablochkoff type. The ones shown in the cut designed for Jablochkoff candles comprise a pair of metallic clamps, each member insulated from the other, and connected as terminals of the circuit. When the candle is placed in position the metal pieces press against the carbons of the candle and thus convey the current. Below each member of the clamps is a binding screw for the line wire terminals.

Fig. 76. JABLOCHKOFF CANDLE HOLDERS.

Fig. 77. JABLOCHKOFF CANDLE.

Candle, Jablochkoff.

An arc lamp without regulating mechanism, producing an arc between the ends of parallel carbons. It consists of two parallel rods of carbon, between which is an insulating layer of non-combustible material called the colombin. Kaolin was originally employed for this part; later, as the fusion of this material was found to short- circuit the arc, a mixture of two parts of calcium sulphate and one of barium sulphate was used. The carbons are 4 millimeters (.16 inch) thick, and the colombin is 3 millimeters (.12 inch) wide and two-thirds as thick. A little slip of carbon is placed across the top, touching both carbons to start the arc. Once started the candle burns to the end, and cannot be restarted after ignition, except by placing a short conductor across the ends, as at first. The Jablochkoff candle may now be considered as virtually extinct in this country. In France at one time a great number were in use.

To keep the carbons of equal length an alternating current must always be used with them. Special alternating combinations were employed in some cases where a direct current had to be drawn upon.

Candle, Jamin.

An arc lamp with approximately parallel carbons, one of which oscillates and is controlled by an electro-magnet and armature. A coil of wire is carried around the carbons to keep the arc steady and in place. The frame and wire coils have been found unsatisfactory, as causing a shadow.

Candle Power.

The amount of light given by the standard candle. The legal English and standard American candle is a sperm candle burning two grains a minute.

It should have burned some ten minutes before use, and the wick should be bent over and have a red tip. Otherwise its readings or indications are useless. A sixteen candle power lamp means a lamp giving the light of sixteen candles. The candle power is a universal unit of illuminating power.

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 gives about 800 candles illumination.

Synonym--Nominal Candle Power.

Candle Power, Spherical.

The average candle power of a source of light in all directions. An arc lamp and an incandescent lamp vary greatly in the intensity of light emitted by them in different directions. The average of a number of determinations at various angles, the lamp being moved about into different positions, is taken for the spherical candle power.

Candle, Standard.

A standard of illuminating power. Unless otherwise expressed the English standard sperm candle is indicated by this term. (See Candle Power.)

Candle, Wilde.

An arc lamp with approximately parallel carbons. One of the carbons can rotate through a small arc being pivoted at its base. This oscillation is regulated by an electro-magnet at its base, and the carbons touch when no current is pa.s.sing. They separate a little when the current pa.s.ses, establis.h.i.+ng an arc. The regulation is comparable to that of a regular arc lamp.

Fig. 78. WILDE CANDLE.

Caoutchouc.

India rubber; a substance existing in an emulsion or solution in the juice of certain trees and vines of the tropics, whence it is obtained by coagulation and drying. The name "rubber" is due to the fact that one of its earliest uses was for erasing pencil marks by rubbing. It has a very high value as an insulator. The unworked crude rubber is called virgin gum; after working over by kneading, it is termed masticated or pure gum rubber; after mixture with sulphur and heating, it is termed vulcanized rubber. If enough sulphur is added it becomes hard, and if black, is termed ebonite; if vermilion or other pigment is also added to produce a reddish color, it is termed vulcanite. The masticated gum dissolves more or less completely in naphtha (sp. gr., .850) benzole, turpentine, chloroform, ether and other similar liquids.. The resistance per centimeter cube of "Hooper's" vulcanized India rubber, such as is used in submarine cables is 1.5E16 ohms. The specific inductive capacity of 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; the same as Specific Inductive Capacity. 'The number expressing it is sometimes called the dielectric constant. (See Capacity, Specific Inductive.)