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thick copper wire, to which it is soldered, and fixed into a wooden ring which prevents contact between the zinc and iron. The vessels contain a mixture of 8 parts water and 1 part oil of vitriol (a mixture which acts by itself ou amalgamated zinc). The battery makes thick platinum wire red hot, yields from 4 to 5 cubic inches of detonating gas per minute, and, though not exactly constant, continues in action for a long time. (Mohr, Pogg. 51, 372.) – According to Sturgeon, the following batteries, each having ten pairs of plates, with a surface of 104 square inches, yield the following quantities of hydrogen gas per minute by the decomposition of water: Sturgeon's, 25; Grove's, 24; Smee's, 15; Daniell's, 12 cubic inches.

Children's Battery consists of forty copper and twenty zinc plates, each 6 feet long and 2 feet 8 inches wide, each zinc plate being placed between two copper plates (Phil. Tr. 1809, p. 32. Schw. 1, 374; 9, 212; 16, 359; also Gilb. 36, 334; 52, 353.)

Wollaston's Cell Apparatus. Zinc (plates are immersed in long and deep, but narrow, copper cells, filled with an acid liquid. The first cell is connected by a semicircular strip of metal with the zinc plate which dips into the second cell, and so on. (Compare Hart, Ed. J. of Sc. 4, 19.) The apparatus of the Florentine Museum consists of six zinc plates. each 85 inches square, immersed in six copper cells. (N. Tr. 6, 1, 219.)—If the cells are made of platinized silver or platinized plated copper (p. 419), and contain a mixture of 1 measure of oil of vitriol with 8 measures of water in which zinc plates are immersed, the battery acts very strongly, and will continue in action for forty-eight hours without requiring fresh acid. (Smee.)

De la Rue (Phil. Mag. J. 9, 484; 10, 244) fills the copper cells with solution of sulphate of copper, and places an amalgamated zinc plate in each (an unamalgamated zinc plate would become covered with copper). The action is stronger than with acids, and no gas is evolved.

Young's Battery (Phil. Mag. J. 10, 241; also Pogg. 40, 625), in which two connected zinc plates are interposed between two connected copper plates, in such a manner that one of the zinc plates is placed between the two copper plates, and one of the copper plates between the two zinc plates, does not possess any particular advantage.

B. The surface of the negative metal not greater than that of the positive

metal. Simple Trough or Cell-Apparatus. Oblong troughs of earthenware are divided into cells by earthenware partitious. Each cell contains a pair of plates of the two metals not in contact with each other; the positive plate of the first cell is connected by a curved strip of metal witli the negative plate of the second cell, &c., &c. All the cells contain the same liquid.— The number of pairs used in this kind of battery is, for the most part, greater than in those previously described; hence the tension is greater; but the quantity, unless very large plates are used, is smaller.

The battery of the Royal Institution of London consists of 2000 pairs of plates, each plate having a surface of 32 square inches on one side. At the Ecole Polytechnique, in Paris, there is a trough battery of 600 pairs of plates, each plate having a surface of 11 square ivches. (GayLussac & Thenard, Recherches, 1, 1.)

In the Cup-apparatus (Couronne des tasses) a number of copper wires bent kuee-shape, and each having a ball of zinc fused on to one of its extremities, are immersed in a series of glasses containing dilute acid, in such a manner, that the zinc end of each wire dips into one glass and the copper end into the next. The action is but slight, on account of the small surface of the metals.

If twenty-four bent iron wires be covered at one end with peroxide of lead (by precipitation in the voltaic circle), and their ends made to dip into twenty-four glasses containing 1 part of nitric acid in 100 parts of water, each glass containing the clean end of one wire and the coated end of another, a battery is obtained which gives slight shocks, but loses its power as the peroxide of lead dissolves. (Schönbein.)-An apparatus of twelve platinum and twelve passive iron wires, immersed in nitric acid of sp. gr. 1.35, produces a very feeble current, which scarcely decomposes iodide of potassium, and has no effect on sulphate of copper or acidulated water. (Schönbein.)

In the Voltaic Pile, properly so called, the pairs of plates are disposed in alternate horizontal layers, with pasteboard, woollen cloth, or felt, saturated with a saline solution of dilute acid, &c. It acts like the trough-battery, but evolves less electricity in a given time, because the contact of the liquid with the metals is less complete.

Instead of plates of copper, Straub (Schweiz. naturw. Anzeiger, Jahrg. 4, S. 7) recommends layers of carbonaceous matter. To prepare these, 7 parts of beech-wood charcoal, in fine powder, are mixed with 4 parts of wheat-flour, and a proper quantity of water, into a paste; the paste is then moulded by pressure into flat circular pieces; and these, after being dried in sand in the open air, are exposed for three or four days to a continually increasing heat, till they smell like burnt bread. They are then ground quite smooth upon sand-stone, ignited between charcoal powder, and ground again. Before using them, they are soaked in water; after use, they are steeped in dilute hydrochloric acid to free them from zinc, and then washed.

De Luc's or Zamboni's Pile. The so-called Dry Pile is usually formed of thin sheets of metal separated by paper,—e. g., of discs of so-called gold and silver paper, joined together by their paper surfaces or of silver paper having its paper side smeared with honey, and then sprinkled with peroxide of manganese. Since the number of plates in these piles can easily be raised to several thousands, the poles exhibit sufficient tension to give sparks. But the quantity of the electric current, which can arise from nothing but the chemical action of the hygroscopic water in the paper on the tin of the so-called silver paper, is extremely small. Hence the poles, after being discharged, take a long time to recover their former tension; the pile produces no ignition of metallic wires, and does not readily exhibit chemical action. It was only by employing plates of greater size than those generally used, that Bohnenberger obtained a slight decomposition of water. — The pile when perfectly dry gives no more electricity (Parrot, H. Davy), and the quantity which it yields is greater in proportion to the quantity of moisture which it contains. (Parrot.). If the pile be dried by surrounding it with chloride of calcium, and raising its temperature, it will afterwards exhibit no electricity at ordinary temperatures, but will become electrical when heated. At temperatures between 70° aud 75°, the tension of the poles is even greater than in an undried pile at ordinary temperatures. But when the poles have been discharged, the accumulation of electricity in the dried pile is much slower than in one which has not been perfectly dried. (Jäger.)

In the undried pile also, the tension of the poles is increased by heating to 24°; the application of a stronger heat produces no perceptible increase of tension. In vacuo, the pile exhibits the same tension as in the air. If the positive pole be connected with the conductor of an electrical machine, the negative electricity of the opposite pole sinks to 0; but when the negative pole is connected with the conductor, the tension of the positive pole increases. (Donné.) After the lapse of some time, the tin of the silver paper becomes dull and tarnished (H. Davy), and the pile gradually loses the whole of its power. (Jäger.)

Comp. Zamboni (Gilb. 60, 151); Heinrich, Schübler, Schweigger (Schw. 15, 113, 126, 132); Jäger (Gilb. 62, 227); Donné (Ann. Chim, Phys. 42, 71,-abstr. Schw. 58, 81); Rosenchöld (Pogg. 43, 193, and 440.)

3. Batteries consisting of one Metal and one Liquid. If square pieces with long tails be cut out of zinc or tin-foil, and placed in about thirty watch-glasses filled with water, and arranged near one another, so that a square may lie in one watch-glass and the strip attached to it in the next,—and consequently each watch-glass, excepting the first and last may contain a square and a strip belonging to two different pieces of metal,—the arrangement thus produced will be Zamboni's Pile of two Elements. In such a case, according to Zamboni, the first watch-glass into which the first square dips, or the pole towards which all the squares are directed, is negative,-and the last watch-glass into which the last strip dips, or the pole towards which all the strips are directed, positive. With copper-foil, the opposite arrangement of the poles takes place. [According to this, the piece of zinc or tin of greater surface must be negative towards that of smaller surface, and the contrary with copper.] But, according to Erman, the positive pole in the zinc-foil arrangement is that towards which the squares are directed, and the negative pole that towards which all the points are directed; the contrary with silver. According to Erman, also, the current continues for two days only at the utmost, and may then be reproduced for a shorter time by the addition of common salt to the water.

If pieces of so-called gold-paper (or silver-paper) be formed into a pile, the metallic pole of this pile" is positive, the paper pole negative. (Erman.) [Is the surface of the metal which is turned towards the paper less smooth than the outer surface ?]

If eighty zinc plates, 4 square inches in surface, polished on one side and rough on the other, be placed in a wooden trough at the distance of 1 or 2 millimetres from one anotber, so that they may be separated by thin strata of air, and one pole of this pile be connected with the electroscope, the other with the ground,--the electroscope receives a considerable charge. The two surfaces of the zinc, being of different degrees of smoothness, act like two metals, and the film of air supplies the place of a liquid. (Watkins, Pogg. 14, 386.) [This deserves verification.]

On filling a number of copper vessels, 1, 2, 3, 4, 5, 6, 7, 8, with dilute sulphuric acid, connecting 1 with 2, 3 with 4, 5 with 6, and 7 with 8, by means of brass wires,-on the other hand, 2 with 3, 4 with 5, and 6 with 7, by means of bundles of thread saturated with salt-water,—and heating only the vessels 1, 3, 5, and 7,—a current is produced, sufficient, when fourteen vessels are used, to decompose water, if the electricity be conducted through that liquid by means of brass wires. As the heated vessels cool, the current ceases. (Schweigger, N. Gehl. 9, 704.)

4. Batteries consisting of one Metal and two or three Liquids. If a number of U-tubes (App. 5) be filled on one side with concentrated, on the other with dilute sulphuric or nitric acid, and connected by arcs of the same metal dipping into the liquids.g., tin, lead, iron, cop, per, or silver-an efficient battery is obtained. With sulphuric acid and iron, positive electricity goes from the end of the arc which dips into the dilute acid to that which dips into the strong acid; the contrary with tin and sulphuric acid. (Faraday, p. 400.)

If one end of tlie copper arc be immersed in solution of liver of sulphur, the other in dilute sulphuric acid, the solution of liver of sulphur being connected with the acid by a film of solution of common salt, a powerful battery is produced. (H. Davy.)

In a pile consisting of the following elements—cloth saturated with water, plate of metal (lead, copper, or silver plates answer best), cloth soaked in solution of liver of sulphur, cloth soaked in water, plate of metal, &c.-positive electricity goes through the metallic arc from the last element to the first. (H. Davy.)

5. Grove's Gas Battery. This battery consists of a series of tubes, containing strips of platinum foil covered with a pulverulent deposit of the same metal. The tubes are arranged in pairs in separate vessels of dilute sulphuric acid; and of each pair, one tube is charged with oxygen and the other with hydrogen gas, in quantities such as to allow the platinum to project above the dilute acid into the atmosphere of gas in the upper part of the tube. The platinum in the oxygen of one pair is metallically connected with the platinum in the hydrogen of the next; and thus a series may be composed of any number of pairs.—A battery of four cells constructed in this manner will decompose acidulated water; a single cell will decompose iodide of potassium; and twenty pairs will produce very powerful effects,—such as giving a shock which may be felt by several persons at once, producing a brilliant light between charcoal points, &c. When the poles are unconnected, a gold-leaf electroscope connected with either of them is sensibly deflected. When distilled water is substituted for acidulated water in the cells of the battery, the effects are similar but more feeble.

The current of positive electricity proceeds, within the battery, from the hydrogen tube to the oxygen tube in the same pair,—so that in the voltameler, the platinum connected with the terminal oxygen tube of the battery becomes the positive pole or anode (vid. Electrolysis, p. 431). In fact, the hydrogen in the battery tubes is the oxidable body, acting like the zinc in the ordinary battery. Both gases in the battery tubes are absorbed,—but the hydrogen twice as fast as the oxygen. It is essential that the platinum plates be immersed in the gases as well as in the liquid: for when these plates are made so short as not to project above the liquid, no action takes place. The use of the finely divided platinum is, of course, to increase the surface of contact. The rationale of the action appears to be as follows: "When the circuit is completed—at each point of contact of oxygen, water, and platinum, a molecule of hydrogen leaves its associated molecule of oxygen to unite with a molecule of the free gas; the oxygen thus thrown off unites with the hydrogen of the adjoining molecule of water; and so on,-till the last molecule of oxygen unites with a molecule of free hydrogen :--or we may conversely assume that the action commences in the hydrogen tube.”

Mr. Grove likewise tried various other combinations of gases, viz. chlorine and hydrogen, chlorine and carbonic oxide, oxygen and nitrous oxide, oxygen and nitric oxide, hydrogen and carbonic oxide, &c.; but none of them were found to be adapted for actual use in the battery. Chlorine and hydrogen gave a powerful current; but the rapid absorption of the chlorine soon put a stop to the action. Chlorine and oxygen, on the one side, and hydrogen and carbonic oxide, on the other, were the only gases which appeared to be decidedly capable of combining electrosynthetically, so as to produce a voltaic current. The other combinations produced no effect, excepting for the first few minutes. Olefiant gas should perhaps be excepted: it appears to give a continuous but feeble current. The vapours of bromine and iodine, were they less soluble, would probably also be found efficient as electro-negative gases. (Phil. Mag. J. 21, 417; 24, 268, 346 and 422.) T

I. Electricity developed by the Vital Process. Certain fishes, as Torpedo unimaculata, marmorata, Galvanii (the Electric Eel), and Narke (the Electric Ray); Silurus electricus; Tetraodon electricus, and Gymnotus electricus, have the power of constantly generating the two electricities in their bodies, in large quantity and of considerable tension, and imparting electric shocks. - In the Electric Ray, negative electricity proceeds from the under, positive electricity from the upper surface of the body. The electricity, when conducted away by wires, acts upon the magnetic needle, and decomposes liquids. (J. Davy.) Sparks may also be obtained from the Electric Ray by means of a peculiar apparatus. (Linari & Matteucci.) Comp. Humboldt (Ann. Chim. Phys. 11, 415); J. Davy (Phil. Trans. 1829, 15; also Schw. 57, 17; also Pogg. 16, 311;--Phil. Trans. 1832, 259; also Pogg. 27, 542); Linari & Matteucci (Pogg. 38, 292); Matteucci (Pogg. 39, 485); Linari (Pogg. 40, 642); Colladon (Pogg. 39, 411).

Faraday has examined the electric force of the Gymnotus. He finds that the shock is strongest when one band is applied to the head and the other to the tail,--and diminishes in force as the points of contact are brought closer together. The galvanometer was affected, and iodide of potassium decomposed--in such a manner as to show that the current proceeds from the anterior towards the posterior part of the fish. The spark was also obtained by means of a magneto-electric coil. When the shock was strong, it was like that of a large Leyden battery charged to a low degree, or that of a voltaic battery of perhaps one hundred and forty or more pairs, of which the circuit is completed for a minute only. (Phil. Trans. 1839, I, 1; Phil. Mag. J. 14, 211.)

The spark had previously been obtained from a gymnotus by Fahlberg and Guisan. (De Gymnoto electrico, Tubingen, 1819.) 1.

II. INFLUENCE OF ELECTRICITY ON THE CHEMICAL NATURE OF

PONDERABLE SUBSTANCES. 1. Combinations brought about by Electrical Influence. The combination of the two electricities often causes combustible bodies, which may be present at the place of combination, to unite with oxygen, chlorine, &c.

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