75 STANDARD ELECTRICAL DICTIONARY.
Fig. 53. SECTION OF UPWARD"S BATTERY.
Fig. 54. ELEVATION OF UPWARD"S BATTERY.
Battery, Upward"s.
A primary voltaic cell, the invention of A. Ren?e Upward. Referring to the cuts, the positive plate. Z, is of cast zinc; it is immersed in water, in a porous cup, B. Outside of the porous cup and contained in the battery jar are two carbon plates, C, C, connected together. The rest of the s.p.a.ce between the porous cup and battery jar is packed with crushed carbon, and the top is cemented. Chlorine gas is led by a pipe, D, into the outer cell. It diffuses through the fine carbon, dissolves in the water, and so finds its way to the zinc, which it attacks, directly combining therewith, and forming zinc chloride (Zn + 2 Cl = Zn Cl 2). Such of the chlorine as is not absorbed finds its way by an outlet tube, E, to the next cell. Arrangements are provided for generating chlorine gas as required. The high specific gravity of the gas is utilized in regulating its distribution through the cells. The electro-motive force of the cell is 2.1 volts. A cell 11.5 by 5.5 inches and 12.5 inches deep has a resistance of 0.2 ohm.
An overflow pipe, F, with faucet, T, is supplied to withdraw the solution of zinc chloride as it acc.u.mulates.
76 STANDARD ELECTRICAL DICTIONARY.
Battery, Varley"s.
A Daniell battery of the Siemens" and Halske"s type (see Battery, Siemens" and Halske"s), in which zinc oxide is subst.i.tuted for the paper pulp of the other battery. It has been very little used.
Battery, Volta"s.
The original acid battery. It has a negative electrode of copper, a positive electrode of zinc; the excitant is sulphuric acid diluted with sixteen times its volume of water. It rapidly polarizes, and is very little used.
Battery, Voltaic or Galvanic.
An apparatus for converting chemical energy directly into electric energy. This is as broad a definition as can well be given. The general conception of a battery includes the action of electrolysis, a solution in the battery acting upon one of two conducting electrodes immersed in such fluid, which dissolves one of them only, or one more than the other. The best way to obtain a fundamental idea of a battery is to start with the simplest. Dilute sulphuric acid dissolves neither pure zinc nor copper. But it has a far stronger affinity for the first named metal. If now we immerse in dilute acid two plates, one of pure zinc, and one of copper, no action will be discernible. But if the plates are brought in contact with each other a stream of bubbles of hydrogen gas will escape from the surface of the copper and the zinc will dissolve.
By applying proper tests and deductions it will be found that the copper and zinc are being constantly charged with opposite electricities, and that these are constantly recombining. This recombination produces what is known as an electric current.
To const.i.tute a battery the zinc and copper plates must be connected outside of the solution. This connection need not be immediate. Any conductor which touches both plates will bring about the action, and the current will pa.s.s through it.
The easiest way to picture the action of a battery is to accept the doctrine of contact action. In the battery the molecules of water are pulled apart. The hydrogen molecules go to the copper, the oxygen molecules go to the zinc, each one, leaving its contact with the other, comes off charged with opposite electricity. This charges the plates, and the continuous supply of charge and its continuous discharge establishes the current.
The acc.u.mulation of hydrogen acts to stop the action by polarization.
Its own affinity for oxygen acts against or in opposition to the affinity of the zinc for the same element, and so cuts down the action.
A depolarizer of some kind is used in acid batteries for this reason. As such depolarizer has only to act upon one plate, in most batteries it is usual to surround such plate only, as far as it is possible, with the depolarizer. The solution which dissolves the zinc is termed the excitant or exciting solution.
To this concrete notion of a voltaic battery the different modifications described here may be referred. Zinc, it will be seen, forms the almost universally used dissolved plate; carbon or copper forms the most usual undissolved plate; sulphuric acid in one form or another is the most usual excitant.
The solution in a voltaic battery is electrolyzed (see Electrolysis).
Hence the solutions must be electrolytes. The sulphuric acid and other ingredients play a secondary role as imparting to the battery fluids this characteristic.
It is not necessary to have electrodes of different substances, the same metal maybe used for both if they are immersed in different solutions which act differentially upon them, or which act with more energy on one than on the other. Such are only of theoretical interest.
77 STANDARD ELECTRICAL DICTIONARY.
Battery, Water.
A voltaic battery, whose exciting fluid is water. They are used for charging quadrant electrometer needles and similar purposes. They polarize very quickly and are of high resistance. Hence very small plates in large number can be used without impairing their advantage.
Rowland"s water battery dispenses with cups and uses capillarity instead. The zinc and platinum or copper plates of a couple are placed very close together, while the couples are more distant. On dipping into water each couple picks up and retains by capillarity a little water between its plates, which forms the exciting fluid. Many hundred couples can be mounted on a board, and the whole is charged by dipping into water and at once removing therefrom. It then develops its full potential difference.
Fig. 55. SECTION OF WOLLASTON BATTERY.
Fig. 56. PLATES OF WOLLASTON"S BATTERY.
78 STANDARD ELECTRICAL DICTIONARY.
Battery, Wollaston.
The original plunge battery is attributed to Wollaston. He also invented the battery known by his name, having the disposition shown in the cut, of zinc Z, surrounded by a thin sheet of copper C; o, o", o", are the terminals and B, B, the battery jars. Dilute sulphuric acid is used for exciting fluid.
B. A. U.
Abbreviation for British a.s.sociation unit, referring generally to the B.
A. unit of resistance.
B. A. Unit of Resistance.
The original ohm used under that name previous to 1884. The Paris committee of that year recommended as a practical unit what is known as the legal ohm. (See Ohm, Legal.) 1 Legal Ohm = 1.0112 B. A. Units of Resistance.
1 B. A. Unit of Resistance = .9889 Legal Ohms.
1 B. A. Unit of Resistance = .98651E9 C. G. S. units.
B. E. adj.
British Engineering, a qualification of a set of units, the B. E. units, having for base the foot and pound. The term is but little used.
Beaum? Hydrometer.
A hydrometer graduated on the following principle:
The zero point corresponds to the specific gravity of water for liquids heavier than water. A solution of 15 parts of salt in 85 parts of water corresponds in specific gravity to 15? B., and between that and zero fifteen equal degrees are laid out. The degrees are carried down below this point.
The zero points for liquids lighter than water correspond to the specific gravity of a solution of 10 parts of salt in 90 parts of water.
The specific gravity of water is taken as 10? B. This gives ten degrees which are continued up the scale.
Becquerel"s Laws of Thermoelectricity.
These are stated under the heads, Law of Intermediate Metals and Law of Successive Temperatures, q. v.
Bed Piece.
In a dynamo or motor the frame carrying it, including often the standards in which the armature shaft is journaled, and often the yoke or even entire field magnet core.