Synonym--Sulphate of Mercury Battery.

Battery, Maynooth's.

A battery of the Bunsen type, with cast iron negative plate. The iron takes the pa.s.sive form and is not attacked.

Battery, Medical.

A term applied very indiscriminately to medical current generators, and to medical induction coils, or to any source of electricity, static or current, for medical application.

68 STANDARD ELECTRICAL DICTIONARY.

Battery, Meidinger's.

A variety of Daniell cell of the gravity type. The plates are cylindrical. The zinc plate lies against the upper walls of the vessel.

The copper plate of smaller diameter rests on the bottom. A large tube, with an aperture in its bottom, is supported in the centre and is charged with copper sulphate crystals. The cup is filled with a dilute solution of Epsom salts (magnesium sulphate) or with dilute sulphuric acid.

Battery Mud.

A deposit of mud-like character which forms in gravity batteries and which consists of metallic copper precipitated by the zinc. It indicates wasteful action.

Battery, Multiple-connected.

A battery connected in parallel, all the positive plates being connected to one electrode, and all the negative to another.

Battery, Nitric Acid.

A battery in which nitric acid is used as the excitant. Owing to its cost and volatility this acid has been but little used in batteries, other than as a depolarizer. In Grove's battery (see Battery, Grove's) it has been thus used.

Battery of Dynamos.

A number of dynamos may be arranged to supply the same circuit. They are then sometimes termed as above, a Dynamo Battery. They may be arranged in series or in parallel or otherwise combined.

Battery of Leyden Jars.

To produce the quant.i.ty effect of a single large Leyden jar with a number of small ones they are often connected in parallel and termed a battery. In such case the inner coatings are all connected by regular bar conductors, and the outside coatings are also all in connection.

They are conveniently placed in a box or deep tray whose inner surface is lined with tinfoil, with an outside connection for grounding, etc.

The cascade, q. v., arrangement is not so generally termed a battery.

Battery, Open Circuit.

A battery adapted for use in open circuit work. Its main requirement is that it shall not run down, or exhaust itself when left on open circuit.

The Leclanch? battery is very extensively used for this work. Its action is typical of that of most open circuit batteries. It is without any action on open circuit. It is very quickly exhausted on closed circuit, but recuperates or depolarizes quite soon when on open circuit. It is always in condition for a momentary connection, but useless for steady work.

Battery, Oxide of Copper.

A battery with zinc positive and iron negative electrodes. The excitant is a 30 or 40 per cent. solution of sodium or pota.s.sium hydrate (caustic soda or caustic potash). The depolarizer is copper oxide. In action the copper is gradually reduced to the metallic state. The iron element is often the containing vessel. The battery is practically inactive on open circuit.

Its electro-motive force varies from .75 to .90 volt. To prevent the formation of sodium or pota.s.sium carbonate the cell should be closed, or else the liquid should be covered with mineral oil.

Synonyms--Lalande & Chaperon Battery--Lalande-Edison Battery.

69 STANDARD ELECTRICAL DICTIONARY.

Battery, Peroxide of Lead.

A battery in which peroxide of lead (lead binoxide) is the depolarizer.

It is a sort of predecessor of the present secondary battery.

Battery, Platinized Carbon.

A modification of Smee's battery, in which platinized carbon is used for the negative plates. Before polarization the E. M. F. is equal to that of Smee's battery. Polarization reduces its electro-motive force one-half.

Battery, Plunge.

A battery whose plates are mounted so as to be immersed in the battery cups or cells, when the battery is to be used, and withdrawn and supported out of the cups when not in use. The object is to prevent wasting of the plates by standing in the solution. It is a construction generally used with sulphuric acid--chromic acid solution and amalgamated zinc and carbon plates.

Battery, Pneumatic.

A battery arranged to have air blown through the solution to a.s.sist diffusion and depolarization. It is a construction applied to chromic acid or bichromate batteries.

Battery, Primary.

A battery in which the current is supplied by the solution of one of the plates by the solution. The term distinguishes it from a secondary or storage battery.

Battery, Pulvermacher's Electro-Medical.

In this battery, the electrodes were zinc and copper wires wound upon small pieces of wood. Dilute vinegar was used as the excitant, because it could be found in every household. Formerly the battery had great success. It is now little used.

Battery, Sal Ammoniac.

Batteries in which a solution of ammonium chloride is the excitant; they are very extensively used on open circuit work. (See Battery, Leclanch?.)

The crystals formed in these batteries have been a.n.a.lyzed and found to consist of ammonium zinc chloride, 3 Zn Cl2, 8 N H3, 4 H20.

Battery, Salt, or Sea Salt.

Batteries in which a solution of sodium chloride or common salt is the excitant, have been largely used, especially for telegraphic purposes.

The Swiss telegraphs use a carbon-zinc combination with salt and water as the excitant. The batteries are sometimes mounted as plunge batteries. They are exhausted by short circuiting after some hours, but recuperate on standing. The zinc is not amalgamated.

70 STANDARD ELECTRICAL DICTIONARY.

Battery, Sand.

A battery whose cells are charged with sand saturated with dilute acid.

It prevents spilling of acid. It is now practically obsolete.