Nerve Currents.
Currents of electricity obtained from nerves. They are much more feeble than those obtained from muscle, but are produced in the same general ways.
Network.
Conductors in parallel and crossing each other, with connections at the junctions.
The term is sometimes so loosely applied as to include parallel conductors.
Neutral Line of Commutator.
The diameter of a commutator which connects its Neutral Points, q. v.; sometimes termed the diameter of commutation; the diameter approximately at right angles with the lines of force. The commutator brushes are applied at the extremities of this diameter.
Neutral Point of a Commutator.
The points of a commutator at which no lines of force are cut; the points at the extremities of a diameter which, except for the lag, would be at right angles to the lines of force; the points at which the brushes touch the commutator.
Neutral Point, Thermo-electric.
A temperature marking a point of no thermo-electric difference of potential. If the junctions of a thermo-electric couple are at temperatures, one a little over and the other an equal amount under the neutral point, no current will be developed. At the neutral point the thermo-electric polarities are reversed. Differences of temperature above it give currents of reverse direction to those given by corresponding differences below it. For an iron-copper couple the neutral point is 274.5? C. (526? F.)
Synonym--Neutral Temperature.
Neutral Relay Armature.
An unpolarizable armature for use with a relay; an armature of soft iron or iron wire; as distinguished from a polarized armature.
391 STANDARD ELECTRICAL DICTIONARY.
Neutral Wire.
The central wire in the three wire system, q. v., of electric distribution; the wire connected to a point between the two dynamos, or otherwise to the central point of the current generator.
Fig. 250. DIAGRAM OF THREE WIRE SYSTEM SHOWING NEUTRAL WIRE.
Neutral Wire Ampere Meter.
An ampere meter connected in the circuit of the neutral wire to determine the current pa.s.sing through it. Such determination is for the purpose of ascertaining how much more work is being done by one of the lateral leads than by the other.
Synonym--Balance Ampere Meter.
N. H. P.
Symbol or contraction for "nominal horse power." This is a basis for rating the size of an engine.
Nickel.
A metal; one of the elements; atomic weight, 58.8 ; equivalent, 29.4; valency, 2; specific gravity, 8.8. It is a conductor of electricity.
Relative resistance, annealed (Silver = 1), 8.285 Specific Resistance, 12.47 microhms.
Resistance of a wire (a) 1 foot long, weighing 1 grain, 15.206 ohms.
(b) 1 foot long, 1/1000 inch thick, 74.963 "
(c) 1 meter long, weighing 1 gram, 1.060 "
(d) 1 meter long, 1 millimeter thick, .1587 "
Resistance of a 1-inch cube, 4.907 microhms.
Electro-chemical equivalent, (Hydrogen = .0105) .3087 mgs.
It is strongly paramagnetic, but loses this quality at 350? C. (662? F.)
It is important as a const.i.tuent of German silver, an alloy much used for resistance coils.
Nickel, Bath.
A bath for the electro-deposition of nickel. A great many formulae have been given. Metallic nickel is dissolved in 1 vol.
sulphuric acid mixed with 2 vols. water. Neutralize with ammonia, and add of ammonium sulphate one-half the weight of metallic nickel originally used; 135 parts of nickel will be enough for a bath of 10,000 parts.
392 STANDARD ELECTRICAL DICTIONARY.
Other formulae are as follows: Double nickel-ammonium sulphate, 4 parts.
Ammonium carbonate, 3 "
Water 100 "
Nickel sulphate, nitrate or chloride, 1 "
Sodium bisulphate, 1 "
Water, 20 "
Nickel anodes are used in the bath to maintain the strength. Too much care cannot be exercised in the absolute cleanliness of the articles to be plated. A too alkaline bath gives a disagreeable yellow color to the deposit; too acid a bath gives badly adhering deposits.
Night Bell.
An alarm bell in a telegraph office, which bell is connected at night to give a loud signal to attract the operator"s attention. It is used in telephone exchanges and is connected so as to ring as long as a subscriber remains unanswered after calling.
n.o.bili"s Rings.
When a dilute solution of copper acetate is placed on a bright silver plate and a strip of zinc is touched to the silver beneath the copper, a series of rings of copper are formed by electrolysis around the zinc.
These are n.o.bili"s rings.
If for the copper acetate a solution of lead oxide in pota.s.sium hydrate solution is subst.i.tuted, and if the polished plate which may be German silver is connected to the positive electrode of a battery, and a platinum wire connected to the negative pole is immersed in the liquid, it determines the formation of beautiful iridescent rings of lead binoxide. The platinum wire is sometimes sealed in gla.s.s so that only its point projects.
The colors are due to interference of light, the layers of lead oxide being extremely thin.
The lead binoxide is formed by secondary reaction. Metallic lead is first deposited on the negative pole. The oxygen which goes to the positive pole formed by the polished plate produces lead binoxide which is deposited there in rings. The reaction is comparable to that of a storage battery.
Synonyms--Metallochromes--Electric Rings.