Chapter 56

1734. It may be said that the state of _no lateral action_ is to static or inductive force the equivalent of _magnetism_ to current force; but that can only be upon the view that electric and magnetic action are in their nature essentially different (1664.). If they are the same power, the whole difference in the results being the consequence of the difference of _direction_, then the normal or _undeveloped_ state of electric force will correspond with the state of _no lateral action_ of the magnetic state of the force; the electric current will correspond with the lateral effects commonly called magnetism; but the state of static induction which is between the normal condition and the current will still require a corresponding lateral condition in the magnetic series, presenting its own peculiar phenomena; for it can hardly be supposed that the normal electric, and the inductive or polarized electric, condition, can both have the same lateral relation. If magnetism be a separate and a higher relation of the powers developed, then perhaps the argument which presses for this third condition of that force would not be so strong.

1735. I cannot conclude these general remarks upon the relation of the electric and magnetic forces without expressing my surprise at the results obtained with the copper plate (1724. 1725.). The experiments with the flat helices represent one of the simplest cases of the induction of electrical currents (1720.); the effect, as is well known, consisting in the production of a momentary current in a wire at the instant when a current in the contrary direction begins to pass through a neighbouring parallel wire, and the production of an equally brief current in the reverse direction when the determining current is stopped (26.). Such being the case, it seems very extraordinary that this induced current which takes place in the helix A when there is only air between A and C (1720.). should be equally strong when that air is replaced by an enormous mass of that excellently conducting metal copper (1721.). It might have been supposed that this mass would have allowed of the formation and discharge of almost any quantity of currents in it, which the helix C was competent to induce, and so in some degree have diminished if not altogether prevented the effect in A: instead of which, though we can hardly doubt that an infinity of currents are formed at the moment in the copper plate, still not the smallest diminution or alteration of the effect in A appears (65.). Almost the only way of reconciling this effect with generally received notions is, as it appears to me, to admit that magnetic action is communicated by the action of the intervening particles (1729. 1733.).

1736. This condition of things, which is very remarkable, accords perfectly with the effects observed in solid helices where wires are coiled over wires to the amount of five or six or more layers in succession, no diminution of effect on the outer ones being occasioned by those within.

§ _22. Note on electrical excitation._

1737. That the different modes in which electrical excitement takes place will some day or other be reduced under one common law can hardly be doubted, though for the present we are bound to admit distinctions. It will be a great point gained when these distinctions are, not removed, but understood.

1738. The strict relation of the electrical and chemical powers renders the chemical mode of excitement the most instructive of all, and the case of two isolated combining particles is probably the simplest that we possess. Here however the action is local, and we still want such a test of electricity as shall apply to it, to cases of current electricity, and also to those of static induction. Whenever by virtue of the previously combined condition of some of the acting particles (923.) we are enabled, as in the voltaic pile, to expand or convert the local action into a current, then chemical action can be traced through its variations to the production of _all_ the phenomena of tension and the static state, these being in every respect the same as if the electric forces producing them had been developed by friction.

1739. It was Berzelius, I believe, who first spoke of the aptness of certain particles to assume opposite states when in presence of each other (959.). Hypothetically we may suppose these states to increase in intensity by increased approximation, or by heat, &c. until at a certain point combination occurs, accompanied by such an arrangement of the forces of the two particles between themselves as is equivalent to a discharge, producing at the same time a particle which is throughout a conductor (1700.).

1740. This aptness to assume an excited electrical state (which is probably polar in those forming non-conducting matter) appears to be a primary fact, and to partake of the nature of induction (1162.), for the particles do not seem capable of retaining their particular state independently of each other (1177.) or of matter in the opposite state. What appears to be definite about the particles of matter is their assumption of a _particular_ state, as the positive or negative, in relation to each other, and not of either one or other indifferently; and also the acquirement of force up to a certain amount.

1741. It is easily conceivable that the same force which causes local action between two free particles shall produce current force if one of the particles is previously in combination, forming part of an electrolyte (923. 1738.). Thus a particle of zinc, and one of oxygen, when in presence of each other, exert their inductive forces (1740.), and these at last rise up to the point of combination. If the oxygen be previously in union with hydrogen, it is held so combined by an analogous exertion and arrangement of the forces; and as the forces of the oxygen and hydrogen are for the time of combination mutually engaged and related, so when the superior relation of the forces between the oxygen and zinc come into play, the induction of the former or oxygen towards the metal cannot be brought on and increased without a corresponding deficiency in its induction towards the hydrogen with which it is in combination (for the amount of force in a particle is considered as definite), and the latter therefore has its force turned towards the oxygen of the next particle of water; thus the effect may be considered as extended to sensible distances, and thrown into the condition of static induction, which being discharged and then removed by the action of other particles produces currents.

1742. In the common voltaic battery, the current is occasioned by the tendency of the zinc to take the oxygen of the water from the hydrogen, the effective action being at the place where the oxygen leaves the previously existing electrolyte. But Schoenbein has arranged a battery in which the effective action is at the other extremity of this essential part of the arrangement, namely, where oxygen goes to the electrolyte[A]. The first may be considered as a case where the current is put into motion by the abstraction of oxygen from hydrogen, the latter by that of hydrogen from oxygen. The direction of the electric current is in both cases the same, when referred to the direction in which the elementary particles of the electrolyte are moving (923. 962.), and both are equally in accordance with the hypothetical view of the inductive action of the particles just described (1740.).

[A] Philosophical Magazine, 1838, xii. 225, 315. also De la Rive's results with peroxide of manganese. Annales de Chimie, 1836, lxi. p. 40.--_Dec. 1838._

1743. In such a view of voltaic excitement, the action of the particles may be divided into two parts, that which occurs whilst the force in a particle of oxygen is rising towards a particle of zinc acting on it, and falling towards the particle of hydrogen with which it is associated (this being the progressive period of the inductive action), and that which occurs when the change of association takes place, and the particle of oxygen leaves the hydrogen and combines with the zinc. The former appears to be that which produces the current, or if there be no current, produces the state of tension at the termination of the battery; whilst the latter, by terminating for the time the influence of the particles which have been active, allows of others coming into play, and so the effect of current is continued.

1744. It seems highly probable, that excitement by friction may very frequently be of the same character. Wollaston endeavoured to refer such excitement to chemical action[A]; but if by chemical action ultimate union of the acting particles is intended, then there are plenty of cases which are opposed to such a view. Davy mentions some such, and for my own part I feel no difficulty in admitting other means of electrical excitement than chemical action, especially if by chemical action is meant a final combination of the particles.

[A] Philosophical Transactions, 1801, p. 427.

1745. Davy refers experimentally to the opposite states which two particles having opposite chemical relations can assume when they are brought into the close vicinity of each other, but _not_ allowed to combine[A]. This, I think, is the first part of the action already described (1743.); but in my opinion it cannot give rise to a continuous current unless combination take place, so as to allow other particles to act successively in the same manner, and not even then unless one set of the particles be present as an element of an electrolyte (923. 963.); i.e. mere quiescent contact alone without chemical action does not in such cases produce a _current_.

[A] Philosophical Transactions, 1807, p. 31.

1746. Still it seems very possible that such a relation may produce a high charge, and thus give rise to excitement by friction. When two bodies are rubbed together to produce electricity in the usual way, one at least must be an insulator. During the act of rubbing, the particles of opposite kinds must be brought more or less closely together, the few which are most favourably circumstanced being in such close contact as to be short only of that which is consequent upon chemical combination. At such moments they may acquire by their mutual induction (1740.) and partial discharge to each other, very exalted opposite states, and when, the moment after, they are by the progress of the rub removed from each other's vicinity, they will retain this state if both bodies be insulators, and exhibit them upon their complete separation.

1747. All the circumstances attending friction seem to me to favour such a view. The irregularities of form and pressure will cause that the particles of the two rubbing surfaces will be at very variable distances, only a few at once being in that very close relation which is probably necessary for the development of the forces; further, those which are nearest at one time will be further removed at another, and others will become the nearest, and so by continuing the friction many will in succession be excited. Finally, the lateral direction of the separation in rubbing seems to me the best fitted to bring many pairs of particles, first of all into that close vicinity necessary for their assuming the opposite states by relation to each other, and then to remove them from each other's influence whilst they retain that state.

1748. It would be easy, on the same view, to explain hypothetically, how, if one of the rubbing bodies be a conductor, as the amalgam of an electrical machine, the state of the other when it comes from under the friction is (as a mass) exalted; but it would be folly to go far into such speculation before that already advanced has been confirmed or corrected by fit experimental evidence. I do not wish it to be supposed that I think all excitement by friction is of this kind; on the contrary, certain experiments lead me to believe, that in many cases, and perhaps in all, effects of a thermo-electric nature conduce to the ultimate effect; and there are very probably other causes of electric disturbance influential at the same time, which we have not as yet distinguished.

_Royal Institution. June, 1838._

INDEX.

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N.B. A dash rule represents the _italics_ immediately preceding it. The references are sometimes to the individual paragraph, and sometimes to that in conjunction with those which follow.

* * * * *

_Absolute_ charge of matter, 1169. ---- quantity of electricity in matter, 852, 861, 873. Acetate of potassa, its electrolysis, 749. Acetates, their electrolysis, 774. Acetic acid, its electrolysis, 773. _Acid_, nitric, formed in air by a spark, 324. ----, or alkali, alike in exciting the pile, 932. ----, transference of, 525. ---- _for battery_, its nature and strength, 1128, 1137. ---- ----, nitric, the best, 1138. ---- ----, effect of different strengths, 1139. ---- _in voltaic pile_, does not evolve the electricity, 925, 933. ---- ----, its use, 925. Acids and bases, their relation in the voltaic pile, 927, 933. Active battery, general remarks on, 1034, 1136. Adhesion of fluids to metals, 1038. Advantages of a new voltaic battery, 1132. _Affinities, chemical_, opposed voltaically, 891, 904, 910. ----, their relation in the active pile, 949. _Air_, its attraction by surfaces, 622. ----, _charge of_, 1173. ----, ----, by brush, 1434, 1441. ----, ----, by glow, 1537, 1543. ----, convective currents in, 1572, 1576, 1581. ----, dark discharge in, 1548. ----, disruptive discharge in, 1359, 1406, 1425, 1526. ----, induction in, 1208, 1215, 1284, 1362. ----, its insulating and conducting power, 411, 1332, 1336, 1362. ----, its rarefaction facilitates discharge, 1375. ----, electrified, 1443. ----, electro-chemical decompositions in, 454, 1623. ----, hot, discharges voltaic battery, 271, 274. ----, poles of, 455, 461, 559. ----, _positive and negative_ brush in, 1467, 1472, 1476. ----, ---- glow in, 1526, 1530. ----, ---- spark in, 1485. ----, rarefied, brush in, 1451, 1456. ----, retention of electricity on conductors by, 1377, 1398. ----, _specific inductive capacity of_, 1284. ----, ----, not varied by temperature or pressure, 1287, 1288. _Alkali_ has strong exciting power in voltaic pile, 884, 931, 941. ----, transference of, 525. _Amalgamated zinc_, its condition, 1000. ----, how prepared, 863. ----, its valuable use, 863, 999. ---- battery, 1001. _Ammonia_, nature of its electrolysis, 748. ----, solution of, a bad conductor, 554, 748. Ampère's inductive results, 78, 255, 379 _note_. _Anions_ defined, 665, 824. ----, table of, 847. ---- related through the entire circuit, 963. ----, their action in the voltaic pile, 924. ----, their direction of transfer, 962, Anode defined, 663. _Antimony_, its relation to magneto-electric induction, 139. ----, chloride of, not an electrolyte, 690, 796. ----, oxide of, how affected by the electric current, 801. ---- _supposed new_ protoxide, 693. ---- ----, sulphuret, 694. _Animal electricity_, its general characters considered, 351. ---- is identical with other electricities, 354, 360. ----, its chemical force, 355. ----, enormous amount, 359. ----, evolution of heat, 353, ----, magnetic force, 351. ----, physiological effects, 357. ----, spark, 358. ----, tension, 352. Apparatus, inductive, 1187. _See_ Inductive apparatus. _Arago's magnetic phenomena_, their nature, 81, 120. ----, reason why no effect if no motion, 126, ----, direction of motion accounted for, 121. ----, due to induced electric currents, 119, 248. ----, like electro-magnetic rotations in principle, 121. ----, not due to direct induction of magnetism, 128, 138, 215, 243, 248. ----, obtained with electro-magnets, 129. ----, produced by conductors only, 130, 215. ----, time an element in, 124. ----, Babbage and Hershel's results explained, 127. Arago's experiment, Sturgeon's form of, 219. Associated voltaic circles, 989. _Atmospheric_ balls of fire, 1611. ----, electricity, its chemical action, 336. Atomic number judged of from electrochemical equivalent, 851. _Atoms of matter_, 869, 1703. ----, their electric power, 856, 860. Attraction of particles, its influence in Döbereiner's phenomena, 619. _Attractions_, electric, their force, 1022 _note_. ----, _chemic, produce_ current force, 852, 918, 947, 996, 1741. ----, ---- local force, 852, 921, 947, 959, 1739. ----, hygrometric, 621. Aurora borealis referred to magneto-electric induction, 192. Axis of power, the electric current on, 517, 1627, 1642.

Balls of fire, atmospheric, 1611. Barlow's revolving globe, magnetic effects explained, 137, 160. Barry, decomposed bodies by atmospheric electricity, 338. Bases and acids, their relation in the pile, 927. Battery, Leyden, that generally used, 291. _Battery, voltaic_, its nature, 856, 989. ----, _origin of its power_, 878, 989. ----, ---- not in contact, 887, 915, ----, ---- chemical, 879, 916, 919, 1741. ----, ----, oxidation of the zinc, 919, 944. ----, its circulating force, 858, 1120. ----, its local force, 1120. ----, quantity of electricity circulating, 990. ----, intensity of electricity circulating, 990, 993. ----, _intensity of its current_, 909, 994. ----, ---- increased, 905, 989. ----, _its diminution in power_, 1035. ----, ---- _from_ adhesion of fluid, 1003, 1136. ----, ---- ---- peculiar state of metal, 1040. ----, ---- ---- exhaustion of charge, 1042. ----, ---- ---- irregularity of plates, 1045, 1146. ----, use of metallic contact in, 893, 896. ----, _electrolytes essential to it_, 921. ----, ----, why, 858, 923. ----, state of metal and electrolyte before contact, 916. ----, conspiring action of associated affinities, 989. ----, purity of its zinc, 1144. ----, use of amalgamated zinc in, 999. ----, _plates, their_ number, 1151. ----, ---- size, 1154. ----, ---- vicinity, 1148. ----, ---- immersion, 1150. ----, ---- relative age, 1146. ----, ---- foulness, 1145. ----, _excited by_ acid, 880, 926, 1137. ----, ---- alkali, 931, 934, 941. ----, ---- sulphuretted solutions, 943. ----, the acid, its use, 925, ----, acid for, 1128, 1137. ----, nitric acid best for, 1137. ----, construction of, 989, 1001, 1121. ----, with numerous alternations, 989. ----, Hare's, 1123. ----, general remarks on, 1031. 1136. ----, simultaneous decompositions with, 1156. ----, practical results with, 1136. ----, _improved_, 1001, 1006, 1120. ----, ----, its construction, 1124. ----, ----, power, 1125, 1128. ----, ----, advantages, 1132. ----, ----, disadvantages, 1132. Batteries, voltaic, compared, 1126. Becquerel, his important secondary results, 745, 784. Berzelius, his view of combustion, 870, 959. Biot's theory of electro-chemical decomposition, 486. Bismuth, its relation to magneto-electric induction, 139. _Bodies_ classed in relation to the electric current, 823. ---- classed in relation to magnetism, 255. Bodies electrolyzable, 824. Bonijol decomposed substances by atmospheric electricity, 336. Boracic acid a bad conductor, 408. _Brush, electric_, 1425. ----, produced, 1425. ----, not affected by nature of conductors, 1454, 1473. ----, is affected by the dielectrics, 1455, 1463, 1475. ----, not dependent on current of air, 1440. ----, proves molecular action of dielectric, 1449, 1450. ----, its analysis, 1427, 1433. ----, nature, 1434, 1441, 1447. ----, form, 1428, 1449, 1451. ----, _ramifications_, 1439. ---- ----, their coalescence, 1453. ----, sound, 1426, 1431. ----, requisite intensity for, 1446. ---- has sensible duration, 1437. ---- is intermitting, 1427, 1431, 1451. ----, _light of_, 1444, 1445, 1451. ----, ----, in different gases, 1446, 1454. ----, dark? 1444, 1552. ----, passes into spark, 1448. ----, spark and glow relation of, 1533, 1539, 1542. ----, in gases, 1454, 1463, 1476. ----, oxygen, 1457, 1476. ----, nitrogen, 1458, 1476. ----, hydrogen, 1459, 1476. ----, coal-gas, 1460, 1476. ----, carbonic acid gas, 1461, 1476. ----, muriatic acid gas, 1462, 1476. ----, rare air, 1451, 1455, 1474. ----, oil of turpentine, 1452. ----, positive, 1455, 1467, 1484. ----, _negative_, 1468, 1472, 1484. ----, ----, of rapid recurrence, 1468, 1491. ----, positive and negative in different gases, 1455, 1475, 1506.